diff --git a/openmeter/app/stripe/calculator.go b/openmeter/app/stripe/calculator.go
index 5a13bc5747..c2e4ecc357 100644
--- a/openmeter/app/stripe/calculator.go
+++ b/openmeter/app/stripe/calculator.go
@@ -12,10 +12,8 @@ import (
 )
 
 // NewStripeCalculator creates a new StripeCalculator.
-func NewStripeCalculator(currencyCode currencyx.Code) (StripeCalculator, error) {
-	currency, err := currencyx.NewCurrencyBuilder(currencyx.CurrencyTypeFiat).
-		WithCode(currencyCode).
-		Build()
+func NewStripeCalculator(currencyCode currencyx.FiatCode) (StripeCalculator, error) {
+	currency, err := currencyCode.AsFiatCurrency()
 	if err != nil {
 		return StripeCalculator{}, fmt.Errorf("failed to get stripe calculator: %w", err)
 	}
diff --git a/openmeter/app/stripe/client/invoice.go b/openmeter/app/stripe/client/invoice.go
index fa4b7584e6..f7814020da 100644
--- a/openmeter/app/stripe/client/invoice.go
+++ b/openmeter/app/stripe/client/invoice.go
@@ -144,7 +144,7 @@ type CreateInvoiceInput struct {
 	InvoiceID                    string
 	AutomaticTaxEnabled          bool
 	CollectionMethod             billing.CollectionMethod
-	Currency                     currencyx.Code
+	Currency                     currencyx.FiatCode
 	DaysUntilDue                 *int64
 	StatementDescriptor          *string
 	StripeCustomerID             string
diff --git a/openmeter/billing/charges/creditpurchase/service/create.go b/openmeter/billing/charges/creditpurchase/service/create.go
index e4a06d5bec..c83c48d590 100644
--- a/openmeter/billing/charges/creditpurchase/service/create.go
+++ b/openmeter/billing/charges/creditpurchase/service/create.go
@@ -95,9 +95,8 @@ func (s *service) buildInvoiceCreditPurchaseGatheringLine(charge creditpurchase.
 
 	// Total cost = credit amount * cost basis (e.g., 100 credits * $0.5 = $50)
 	totalCost := intent.CreditAmount.Mul(invoiceSettlement.CostBasis)
-	calc, err := currencyx.NewCurrencyBuilder(currencyx.CurrencyTypeFiat).
-		WithCode(invoiceSettlement.Currency).
-		Build()
+	invoiceCurrency := currencyx.FiatCode(invoiceSettlement.Currency)
+	calc, err := invoiceCurrency.AsFiatCurrency()
 	if err != nil {
 		return billing.GatheringLine{}, fmt.Errorf("creating currency calculator: %w", err)
 	}
@@ -134,7 +133,7 @@ func (s *service) buildInvoiceCreditPurchaseGatheringLine(charge creditpurchase.
 					},
 				),
 			),
-			Currency:      invoiceSettlement.Currency,
+			Currency:      invoiceCurrency,
 			ServicePeriod: intent.ServicePeriod,
 			InvoiceAt:     intent.CalculateEffectiveAt(),
 			TaxConfig:     lo.ToPtr(intent.TaxConfig.ToTaxConfig()),
diff --git a/openmeter/billing/charges/flatfee/charge.go b/openmeter/billing/charges/flatfee/charge.go
index 63b0649191..46ef6dc887 100644
--- a/openmeter/billing/charges/flatfee/charge.go
+++ b/openmeter/billing/charges/flatfee/charge.go
@@ -15,6 +15,7 @@ import (
 	"github.com/openmeterio/openmeter/openmeter/currencies"
 	"github.com/openmeterio/openmeter/openmeter/customer"
 	"github.com/openmeterio/openmeter/openmeter/productcatalog"
+	"github.com/openmeterio/openmeter/pkg/currencyx"
 	"github.com/openmeterio/openmeter/pkg/models"
 	"github.com/openmeterio/openmeter/pkg/timeutil"
 )
@@ -81,6 +82,25 @@ func (c ChargeBase) GetCurrency() currencies.Currency {
 	return c.Intent.GetCurrency()
 }
 
+func (c ChargeBase) GetInvoiceCurrency() (currencyx.FiatCode, error) {
+	currency := c.GetCurrency()
+	if currency.IsFiat() {
+		return currencyx.FiatCode(currency.GetCode()), nil
+	}
+
+	costBasisIntent := c.Intent.GetCostBasisIntent()
+	if costBasisIntent == nil {
+		return "", errors.New("cost basis intent is required for a custom-currency invoice")
+	}
+
+	fiatCurrency, err := costBasisIntent.GetFiatCurrency()
+	if err != nil {
+		return "", fmt.Errorf("getting cost basis fiat currency: %w", err)
+	}
+
+	return fiatCurrency.GetFiatCode(), nil
+}
+
 func (c ChargeBase) ErrorAttributes() models.Attributes {
 	return models.Attributes{
 		"charge_id":   c.ID,
diff --git a/openmeter/billing/charges/flatfee/service/create.go b/openmeter/billing/charges/flatfee/service/create.go
index 37584dc0d1..087f5e0c06 100644
--- a/openmeter/billing/charges/flatfee/service/create.go
+++ b/openmeter/billing/charges/flatfee/service/create.go
@@ -195,6 +195,11 @@ func buildFlatFeeGatheringLine(input buildFlatFeeGatheringLineInput) (billing.Ga
 		managedBy = billing.ManuallyManagedLine
 	}
 
+	invoiceCurrency, err := flatFee.GetInvoiceCurrency()
+	if err != nil {
+		return billing.GatheringLine{}, fmt.Errorf("getting invoice currency: %w", err)
+	}
+
 	gatheringLine := billing.GatheringLine{
 		GatheringLineBase: billing.GatheringLineBase{
 			ManagedResource: models.NewManagedResource(models.ManagedResourceInput{
@@ -217,7 +222,7 @@ func buildFlatFeeGatheringLine(input buildFlatFeeGatheringLineInput) (billing.Ga
 			),
 			FeatureKey: lo.FromPtr(lineIntent.FeatureKey),
 
-			Currency:      lineIntent.Currency.GetCode(),
+			Currency:      invoiceCurrency,
 			ServicePeriod: lineIntent.ServicePeriod,
 			InvoiceAt:     lineIntent.InvoiceAt,
 
diff --git a/openmeter/billing/charges/flatfee/service/linemapper.go b/openmeter/billing/charges/flatfee/service/linemapper.go
index d1bd014783..62eceb4ecb 100644
--- a/openmeter/billing/charges/flatfee/service/linemapper.go
+++ b/openmeter/billing/charges/flatfee/service/linemapper.go
@@ -8,13 +8,10 @@ import (
 
 	"github.com/openmeterio/openmeter/openmeter/billing"
 	"github.com/openmeterio/openmeter/openmeter/billing/charges/flatfee"
-	"github.com/openmeterio/openmeter/pkg/currencyx"
 )
 
 func populateFlatFeeStandardLineFromRun(stdLine *billing.StandardLine, run flatfee.RealizationRun) error {
-	currency, err := currencyx.NewCurrencyBuilder(currencyx.CurrencyTypeFiat).
-		WithCode(stdLine.Currency).
-		Build()
+	currency, err := stdLine.Currency.AsFiatCurrency()
 	if err != nil {
 		return fmt.Errorf("creating currency calculator: %w", err)
 	}
diff --git a/openmeter/billing/charges/flatfee/service/manualedit.go b/openmeter/billing/charges/flatfee/service/manualedit.go
index b6523b4d55..3c006c1d6c 100644
--- a/openmeter/billing/charges/flatfee/service/manualedit.go
+++ b/openmeter/billing/charges/flatfee/service/manualedit.go
@@ -78,10 +78,11 @@ func intentFromManualCreatedLine(
 		return flatfee.Intent{}, fmt.Errorf("line id is required")
 	}
 
-	currency, err := currencies.NewFiatCurrency(line.GetCurrency())
+	fiatCurrency, err := line.GetCurrency().AsFiatCurrency()
 	if err != nil {
 		return flatfee.Intent{}, fmt.Errorf("resolving fiat currency %q: %w", line.GetCurrency(), err)
 	}
+	currency := currencies.Currency{Currency: fiatCurrency}
 
 	if chargeID := line.GetChargeID(); chargeID != nil && *chargeID != "" {
 		return flatfee.Intent{}, fmt.Errorf("line[%s]: charge id must be empty for manual create", line.GetID())
diff --git a/openmeter/billing/charges/invoiceupdater/invoiceupdate.go b/openmeter/billing/charges/invoiceupdater/invoiceupdate.go
index 9ab26e2f00..e42485a4d9 100644
--- a/openmeter/billing/charges/invoiceupdater/invoiceupdate.go
+++ b/openmeter/billing/charges/invoiceupdater/invoiceupdate.go
@@ -320,7 +320,7 @@ func (u *updater) provisionUpcomingLines(ctx context.Context, customerID custome
 		return nil
 	}
 
-	linesByCurrency := lo.GroupBy(lines, func(l billing.GatheringLine) currencyx.Code {
+	linesByCurrency := lo.GroupBy(lines, func(l billing.GatheringLine) currencyx.FiatCode {
 		return l.Currency
 	})
 
diff --git a/openmeter/billing/charges/models/costbasis/intent.go b/openmeter/billing/charges/models/costbasis/intent.go
index 0bcd9100fb..df22434eb8 100644
--- a/openmeter/billing/charges/models/costbasis/intent.go
+++ b/openmeter/billing/charges/models/costbasis/intent.go
@@ -130,6 +130,36 @@ func (i Intent) AsDynamic() (DynamicIntent, error) {
 	return *i.dynamic, nil
 }
 
+// GetFiatCurrency returns the fiat currency in which the custom-currency cost
+// basis is expressed, regardless of the selected resolution mode.
+func (i Intent) GetFiatCurrency() (*currencyx.FiatCurrency, error) {
+	switch i.kind {
+	case ModeDynamic:
+		intent, err := i.AsDynamic()
+		if err != nil {
+			return nil, err
+		}
+
+		return intent.FiatCurrency, nil
+	case ModePinned:
+		intent, err := i.AsPinned()
+		if err != nil {
+			return nil, err
+		}
+
+		return intent.FiatCurrency, nil
+	case ModeManual:
+		intent, err := i.AsManual()
+		if err != nil {
+			return nil, err
+		}
+
+		return intent.FiatCurrency, nil
+	default:
+		return nil, models.NewGenericValidationError(fmt.Errorf("invalid intent kind: %s", i.kind))
+	}
+}
+
 type DynamicIntent struct {
 	FiatCurrency *currencyx.FiatCurrency
 }
diff --git a/openmeter/billing/charges/service/create.go b/openmeter/billing/charges/service/create.go
index ba2aabd13c..8fa994a177 100644
--- a/openmeter/billing/charges/service/create.go
+++ b/openmeter/billing/charges/service/create.go
@@ -394,7 +394,7 @@ type currencyAndCustomerID struct {
 }
 
 type currencyCodeAndCustomerID struct {
-	currency   currencyx.Code
+	currency   currencyx.FiatCode
 	customerID customer.CustomerID
 }
 
diff --git a/openmeter/billing/charges/service/creditpurchase_test.go b/openmeter/billing/charges/service/creditpurchase_test.go
index a647e0e63a..901697b5a5 100644
--- a/openmeter/billing/charges/service/creditpurchase_test.go
+++ b/openmeter/billing/charges/service/creditpurchase_test.go
@@ -826,7 +826,7 @@ func (s *CreditPurchaseTestSuite) TestStandardInvoiceCreditPurchase() {
 		s.Require().Len(lines, 1)
 
 		line := lines[0]
-		s.Equal(USD, line.Currency)
+		s.Equal(currencyx.FiatCode(USD), line.Currency)
 		s.Equal(timeutil.ClosedPeriod{
 			From: datetime.MustParseTimeInLocation(s.T(), "2026-01-01T00:00:00Z", time.UTC).AsTime(),
 			To:   datetime.MustParseTimeInLocation(s.T(), "2026-02-01T00:00:00Z", time.UTC).AsTime(),
diff --git a/openmeter/billing/charges/service/flatfee_costbasis_test.go b/openmeter/billing/charges/service/flatfee_costbasis_test.go
index 3e82186d4c..eaffb789d2 100644
--- a/openmeter/billing/charges/service/flatfee_costbasis_test.go
+++ b/openmeter/billing/charges/service/flatfee_costbasis_test.go
@@ -140,6 +140,8 @@ func (s *FlatFeeCostBasisCreateSuite) TestCreatePersistsManualPinnedAndDynamicCo
 
 	seenCostBasisIDs := map[string]struct{}{}
 	for idx, result := range created {
+		s.Require().NotNil(result.GatheringLineToCreate, "charge index %d", idx)
+		s.Require().Equal(currencyx.FiatCode("USD"), result.GatheringLineToCreate.Currency, "charge index %d", idx)
 		s.Require().NotNil(result.Charge.State.CostBasisID, "charge index %d", idx)
 
 		reloaded, err := s.mustGetChargeByID(result.Charge.GetChargeID()).AsFlatFeeCharge()
diff --git a/openmeter/billing/charges/service/invoicable_test.go b/openmeter/billing/charges/service/invoicable_test.go
index dffeb4c9bd..938f97f73f 100644
--- a/openmeter/billing/charges/service/invoicable_test.go
+++ b/openmeter/billing/charges/service/invoicable_test.go
@@ -498,7 +498,7 @@ func (s *InvoicableChargesTestSuite) TestFlatFeePartialCreditRealizations() {
 		gatheringInvoices, err := s.BillingService.ListGatheringInvoices(ctx, billing.ListGatheringInvoicesInput{
 			Namespaces: []string{ns},
 			Customers:  []string{cust.ID},
-			Currencies: []currencyx.Code{currencyx.Code(currency.USD)},
+			Currencies: []currencyx.FiatCode{currencyx.FiatCode(currency.USD)},
 			Expand:     []billing.GatheringInvoiceExpand{billing.GatheringInvoiceExpandLines},
 		})
 		s.NoError(err)
@@ -1363,7 +1363,7 @@ func (s *InvoicableChargesTestSuite) TestUsageBasedCreditOnlyLifecycle() {
 		gatheringInvoices, err := s.BillingService.ListGatheringInvoices(ctx, billing.ListGatheringInvoicesInput{
 			Namespaces: []string{ns},
 			Customers:  []string{cust.ID},
-			Currencies: []currencyx.Code{currencyx.Code(currency.USD)},
+			Currencies: []currencyx.FiatCode{currencyx.FiatCode(currency.USD)},
 			Expand:     []billing.GatheringInvoiceExpand{billing.GatheringInvoiceExpandLines},
 		})
 		s.NoError(err)
@@ -2759,7 +2759,7 @@ func (s *InvoicableChargesTestSuite) TestFlatFeeCreditOnlyLifecycle() {
 		gatheringInvoices, err := s.BillingService.ListGatheringInvoices(ctx, billing.ListGatheringInvoicesInput{
 			Namespaces: []string{ns},
 			Customers:  []string{cust.ID},
-			Currencies: []currencyx.Code{currencyx.Code(currency.USD)},
+			Currencies: []currencyx.FiatCode{currencyx.FiatCode(currency.USD)},
 			Expand:     []billing.GatheringInvoiceExpand{billing.GatheringInvoiceExpandLines},
 		})
 		s.NoError(err)
diff --git a/openmeter/billing/charges/service/invoice.go b/openmeter/billing/charges/service/invoice.go
index 4250a605ce..5d7b96efee 100644
--- a/openmeter/billing/charges/service/invoice.go
+++ b/openmeter/billing/charges/service/invoice.go
@@ -88,10 +88,11 @@ func (s *service) handleStandardInvoiceUpdate(ctx context.Context, invoice billi
 		return err
 	}
 
-	currency, err := currencies.NewFiatCurrency(invoice.Currency)
+	fiatCurrency, err := invoice.Currency.AsFiatCurrency()
 	if err != nil {
 		return fmt.Errorf("resolving fiat invoice currency %q: %w", invoice.Currency, err)
 	}
+	currency := currencies.Currency{Currency: fiatCurrency}
 
 	return s.recognizeCustomerEarnings(ctx, invoice.CustomerID(), currency)
 }
diff --git a/openmeter/billing/charges/service/pendinglines.go b/openmeter/billing/charges/service/pendinglines.go
index a2c1a84e3a..051d7eba04 100644
--- a/openmeter/billing/charges/service/pendinglines.go
+++ b/openmeter/billing/charges/service/pendinglines.go
@@ -15,7 +15,6 @@ import (
 	"github.com/openmeterio/openmeter/openmeter/billing/charges/usagebased"
 	"github.com/openmeterio/openmeter/openmeter/currencies"
 	"github.com/openmeterio/openmeter/openmeter/productcatalog"
-	"github.com/openmeterio/openmeter/pkg/currencyx"
 	"github.com/openmeterio/openmeter/pkg/framework/transaction"
 	"github.com/openmeterio/openmeter/pkg/slicesx"
 )
@@ -112,9 +111,7 @@ func validateChargePendingInvoiceLinesInput(input charges.CreatePendingInvoiceLi
 }
 
 func mapPendingInvoiceLinesToChargeIntents(input charges.CreatePendingInvoiceLinesInput) (charges.ChargeIntents, error) {
-	currency, err := currencyx.NewCurrencyBuilder(currencyx.CurrencyTypeFiat).
-		WithCode(input.Currency).
-		Build()
+	currency, err := input.Currency.AsFiatCurrency()
 	if err != nil {
 		return nil, fmt.Errorf("resolving fiat currency %q: %w", input.Currency, err)
 	}
diff --git a/openmeter/billing/charges/service/pendinglines_test.go b/openmeter/billing/charges/service/pendinglines_test.go
index 70376916c8..36615bb3c3 100644
--- a/openmeter/billing/charges/service/pendinglines_test.go
+++ b/openmeter/billing/charges/service/pendinglines_test.go
@@ -10,6 +10,7 @@ import (
 	"github.com/openmeterio/openmeter/openmeter/billing/charges"
 	"github.com/openmeterio/openmeter/openmeter/billing/charges/meta"
 	"github.com/openmeterio/openmeter/openmeter/productcatalog"
+	"github.com/openmeterio/openmeter/pkg/currencyx"
 	"github.com/openmeterio/openmeter/pkg/datetime"
 	"github.com/openmeterio/openmeter/pkg/models"
 	"github.com/openmeterio/openmeter/pkg/timeutil"
@@ -46,7 +47,7 @@ func (s *InvoicableChargesTestSuite) TestCreatePendingInvoiceLinesCreatesChargeB
 			}),
 			ManagedBy:     billing.ManuallyManagedLine,
 			Engine:        billing.LineEngineTypeInvoice,
-			Currency:      USD,
+			Currency:      currencyx.FiatCode(USD),
 			ServicePeriod: servicePeriod,
 			InvoiceAt:     servicePeriod.To,
 			Price: lo.FromPtr(productcatalog.NewPriceFrom(productcatalog.UnitPrice{
@@ -70,7 +71,7 @@ func (s *InvoicableChargesTestSuite) TestCreatePendingInvoiceLinesCreatesChargeB
 		InvoiceAt:     servicePeriod.From,
 		ManagedBy:     billing.ManuallyManagedLine,
 		Name:          "manual flat",
-		Currency:      USD,
+		Currency:      currencyx.FiatCode(USD),
 		PerUnitAmount: alpacadecimal.NewFromInt(10),
 		PaymentTerm:   productcatalog.InAdvancePaymentTerm,
 		RateCardDiscounts: billing.Discounts{
@@ -86,7 +87,7 @@ func (s *InvoicableChargesTestSuite) TestCreatePendingInvoiceLinesCreatesChargeB
 
 	result, err := s.Charges.CreatePendingInvoiceLines(ctx, charges.CreatePendingInvoiceLinesInput{
 		Customer: cust.GetID(),
-		Currency: USD,
+		Currency: currencyx.FiatCode(USD),
 		Lines: []billing.GatheringLine{
 			usageLine,
 			flatLine,
@@ -154,7 +155,7 @@ func (s *InvoicableChargesTestSuite) TestCreatePendingInvoiceLinesRollsBackCreat
 		InvoiceAt:     servicePeriod.From,
 		ManagedBy:     billing.ManuallyManagedLine,
 		Name:          "manual zero flat",
-		Currency:      USD,
+		Currency:      currencyx.FiatCode(USD),
 		PerUnitAmount: alpacadecimal.Zero,
 		PaymentTerm:   productcatalog.InAdvancePaymentTerm,
 	})
@@ -163,7 +164,7 @@ func (s *InvoicableChargesTestSuite) TestCreatePendingInvoiceLinesRollsBackCreat
 
 	result, err := s.Charges.CreatePendingInvoiceLines(ctx, charges.CreatePendingInvoiceLinesInput{
 		Customer: cust.GetID(),
-		Currency: USD,
+		Currency: currencyx.FiatCode(USD),
 		Lines: []billing.GatheringLine{
 			zeroFlatLine,
 		},
@@ -198,14 +199,14 @@ func (s *InvoicableChargesTestSuite) TestCreatePendingInvoiceLinesRejectsNonManu
 		InvoiceAt:     servicePeriod.From,
 		ManagedBy:     billing.SystemManagedLine,
 		Name:          "system flat",
-		Currency:      USD,
+		Currency:      currencyx.FiatCode(USD),
 		PerUnitAmount: alpacadecimal.NewFromInt(10),
 		PaymentTerm:   productcatalog.InAdvancePaymentTerm,
 	})
 
 	_, err := s.Charges.CreatePendingInvoiceLines(ctx, charges.CreatePendingInvoiceLinesInput{
 		Customer: cust.GetID(),
-		Currency: USD,
+		Currency: currencyx.FiatCode(USD),
 		Lines: []billing.GatheringLine{
 			systemLine,
 		},
@@ -219,7 +220,7 @@ func (s *InvoicableChargesTestSuite) TestCreatePendingInvoiceLinesRejectsNonManu
 		InvoiceAt:     servicePeriod.From,
 		ManagedBy:     billing.ManuallyManagedLine,
 		Name:          "subscription flat",
-		Currency:      USD,
+		Currency:      currencyx.FiatCode(USD),
 		PerUnitAmount: alpacadecimal.NewFromInt(10),
 		PaymentTerm:   productcatalog.InAdvancePaymentTerm,
 	})
@@ -232,7 +233,7 @@ func (s *InvoicableChargesTestSuite) TestCreatePendingInvoiceLinesRejectsNonManu
 
 	_, err = s.Charges.CreatePendingInvoiceLines(ctx, charges.CreatePendingInvoiceLinesInput{
 		Customer: cust.GetID(),
-		Currency: USD,
+		Currency: currencyx.FiatCode(USD),
 		Lines: []billing.GatheringLine{
 			subscriptionLine,
 		},
@@ -270,7 +271,7 @@ func (s *InvoicableChargesTestSuite) TestCreatePendingInvoiceLinesRollsBackParti
 			}),
 			ManagedBy:     billing.ManuallyManagedLine,
 			Engine:        billing.LineEngineTypeInvoice,
-			Currency:      USD,
+			Currency:      currencyx.FiatCode(USD),
 			ServicePeriod: servicePeriod,
 			InvoiceAt:     servicePeriod.To,
 			Price: lo.FromPtr(productcatalog.NewPriceFrom(productcatalog.UnitPrice{
@@ -286,7 +287,7 @@ func (s *InvoicableChargesTestSuite) TestCreatePendingInvoiceLinesRollsBackParti
 		InvoiceAt:     servicePeriod.From,
 		ManagedBy:     billing.ManuallyManagedLine,
 		Name:          "manual zero flat",
-		Currency:      USD,
+		Currency:      currencyx.FiatCode(USD),
 		PerUnitAmount: alpacadecimal.Zero,
 		PaymentTerm:   productcatalog.InAdvancePaymentTerm,
 	})
@@ -294,7 +295,7 @@ func (s *InvoicableChargesTestSuite) TestCreatePendingInvoiceLinesRollsBackParti
 
 	result, err := s.Charges.CreatePendingInvoiceLines(ctx, charges.CreatePendingInvoiceLinesInput{
 		Customer: cust.GetID(),
-		Currency: USD,
+		Currency: currencyx.FiatCode(USD),
 		Lines: []billing.GatheringLine{
 			usageLine,
 			zeroFlatLine,
diff --git a/openmeter/billing/charges/service/taxcode_test.go b/openmeter/billing/charges/service/taxcode_test.go
index 88bec931f6..675c65bc7c 100644
--- a/openmeter/billing/charges/service/taxcode_test.go
+++ b/openmeter/billing/charges/service/taxcode_test.go
@@ -410,7 +410,7 @@ func (s *TaxCodePersistenceTestSuite) TestCreditPurchaseInvoiceSettlementPropaga
 	gatheringInvoices, err := s.BillingService.ListGatheringInvoices(ctx, billing.ListGatheringInvoicesInput{
 		Namespaces: []string{ns},
 		Customers:  []string{cust.ID},
-		Currencies: []currencyx.Code{USD},
+		Currencies: []currencyx.FiatCode{currencyx.FiatCode(USD)},
 		Expand:     []billing.GatheringInvoiceExpand{billing.GatheringInvoiceExpandLines},
 	})
 	s.NoError(err)
@@ -529,7 +529,7 @@ func (s *TaxCodePersistenceTestSuite) TestCreditPurchaseInvoiceSettlementNilTaxC
 	gatheringInvoices, err := s.BillingService.ListGatheringInvoices(ctx, billing.ListGatheringInvoicesInput{
 		Namespaces: []string{ns},
 		Customers:  []string{cust.ID},
-		Currencies: []currencyx.Code{USD},
+		Currencies: []currencyx.FiatCode{currencyx.FiatCode(USD)},
 		Expand:     []billing.GatheringInvoiceExpand{billing.GatheringInvoiceExpandLines},
 	})
 	s.NoError(err)
@@ -980,7 +980,7 @@ func (s *TaxCodePersistenceTestSuite) TestFlatFeeInvoiceSettlementPropagatesTaxC
 	gatheringInvoices, err := s.BillingService.ListGatheringInvoices(ctx, billing.ListGatheringInvoicesInput{
 		Namespaces: []string{ns},
 		Customers:  []string{cust.ID},
-		Currencies: []currencyx.Code{USD},
+		Currencies: []currencyx.FiatCode{currencyx.FiatCode(USD)},
 		Expand:     []billing.GatheringInvoiceExpand{billing.GatheringInvoiceExpandLines},
 	})
 	s.NoError(err)
@@ -1040,7 +1040,7 @@ func (s *TaxCodePersistenceTestSuite) TestFlatFeeInvoiceSettlementNilTaxConfigGe
 	gatheringInvoices, err := s.BillingService.ListGatheringInvoices(ctx, billing.ListGatheringInvoicesInput{
 		Namespaces: []string{ns},
 		Customers:  []string{cust.ID},
-		Currencies: []currencyx.Code{USD},
+		Currencies: []currencyx.FiatCode{currencyx.FiatCode(USD)},
 		Expand:     []billing.GatheringInvoiceExpand{billing.GatheringInvoiceExpandLines},
 	})
 	s.NoError(err)
@@ -1111,7 +1111,7 @@ func (s *TaxCodePersistenceTestSuite) TestUsageBasedCreditThenInvoicePropagatesT
 	gatheringInvoices, err := s.BillingService.ListGatheringInvoices(ctx, billing.ListGatheringInvoicesInput{
 		Namespaces: []string{ns},
 		Customers:  []string{cust.ID},
-		Currencies: []currencyx.Code{USD},
+		Currencies: []currencyx.FiatCode{currencyx.FiatCode(USD)},
 		Expand:     []billing.GatheringInvoiceExpand{billing.GatheringInvoiceExpandLines},
 	})
 	s.NoError(err)
@@ -1295,7 +1295,7 @@ func (s *TaxCodePersistenceTestSuite) TestFlatFeeBehaviorOnlyTaxConfigGetsDefaul
 	gatheringInvoices, err := s.BillingService.ListGatheringInvoices(ctx, billing.ListGatheringInvoicesInput{
 		Namespaces: []string{ns},
 		Customers:  []string{cust.ID},
-		Currencies: []currencyx.Code{USD},
+		Currencies: []currencyx.FiatCode{currencyx.FiatCode(USD)},
 		Expand:     []billing.GatheringInvoiceExpand{billing.GatheringInvoiceExpandLines},
 	})
 	s.NoError(err)
@@ -1371,7 +1371,7 @@ func (s *TaxCodePersistenceTestSuite) TestUsageBasedBehaviorOnlyTaxConfigGetsDef
 	gatheringInvoices, err := s.BillingService.ListGatheringInvoices(ctx, billing.ListGatheringInvoicesInput{
 		Namespaces: []string{ns},
 		Customers:  []string{cust.ID},
-		Currencies: []currencyx.Code{USD},
+		Currencies: []currencyx.FiatCode{currencyx.FiatCode(USD)},
 		Expand:     []billing.GatheringInvoiceExpand{billing.GatheringInvoiceExpandLines},
 	})
 	s.NoError(err)
diff --git a/openmeter/billing/charges/service/usagebased_costbasis_test.go b/openmeter/billing/charges/service/usagebased_costbasis_test.go
index 748e0d2893..f8d659dd2c 100644
--- a/openmeter/billing/charges/service/usagebased_costbasis_test.go
+++ b/openmeter/billing/charges/service/usagebased_costbasis_test.go
@@ -140,6 +140,8 @@ func (s *UsageBasedCostBasisCreateSuite) TestCreatePersistsManualPinnedAndDynami
 
 	seenCostBasisIDs := map[string]struct{}{}
 	for idx, result := range created {
+		s.Require().NotNil(result.GatheringLineToCreate, "charge index %d", idx)
+		s.Require().Equal(currencyx.FiatCode("USD"), result.GatheringLineToCreate.Currency, "charge index %d", idx)
 		s.Require().NotNil(result.Charge.State.CostBasisID, "charge index %d", idx)
 
 		reloaded, err := s.mustGetChargeByID(result.Charge.GetChargeID()).AsUsageBasedCharge()
diff --git a/openmeter/billing/charges/usagebased/charge.go b/openmeter/billing/charges/usagebased/charge.go
index ca886df010..1d066ca0a6 100644
--- a/openmeter/billing/charges/usagebased/charge.go
+++ b/openmeter/billing/charges/usagebased/charge.go
@@ -15,6 +15,7 @@ import (
 	"github.com/openmeterio/openmeter/openmeter/customer"
 	"github.com/openmeterio/openmeter/openmeter/productcatalog"
 	"github.com/openmeterio/openmeter/openmeter/productcatalog/feature"
+	"github.com/openmeterio/openmeter/pkg/currencyx"
 	"github.com/openmeterio/openmeter/pkg/models"
 	"github.com/openmeterio/openmeter/pkg/ref"
 	"github.com/openmeterio/openmeter/pkg/timeutil"
@@ -84,6 +85,25 @@ func (c ChargeBase) GetCurrency() currencies.Currency {
 	return c.Intent.GetCurrency()
 }
 
+func (c ChargeBase) GetInvoiceCurrency() (currencyx.FiatCode, error) {
+	currency := c.GetCurrency()
+	if currency.IsFiat() {
+		return currencyx.FiatCode(currency.GetCode()), nil
+	}
+
+	costBasisIntent := c.Intent.GetCostBasisIntent()
+	if costBasisIntent == nil {
+		return "", errors.New("cost basis intent is required for a custom-currency invoice")
+	}
+
+	fiatCurrency, err := costBasisIntent.GetFiatCurrency()
+	if err != nil {
+		return "", fmt.Errorf("getting cost basis fiat currency: %w", err)
+	}
+
+	return fiatCurrency.GetFiatCode(), nil
+}
+
 // GetIntentDeletedAt returns the effective intent deletion timestamp.
 // If an override is present, the override intent owns deletion; otherwise the base intent does.
 func (c ChargeBase) GetIntentDeletedAt() *time.Time {
diff --git a/openmeter/billing/charges/usagebased/service/create.go b/openmeter/billing/charges/usagebased/service/create.go
index f9426e9ba2..266da4992f 100644
--- a/openmeter/billing/charges/usagebased/service/create.go
+++ b/openmeter/billing/charges/usagebased/service/create.go
@@ -118,6 +118,11 @@ func gatheringLineFromUsageBasedChargeForPeriod(charge usagebased.Charge, servic
 		unitConfig = lo.ToPtr(intent.UnitConfig.Clone())
 	}
 
+	invoiceCurrency, err := charge.GetInvoiceCurrency()
+	if err != nil {
+		return usagebased.ChargeWithGatheringLine{}, fmt.Errorf("getting invoice currency: %w", err)
+	}
+
 	gatheringLine := billing.GatheringLine{
 		GatheringLineBase: billing.GatheringLineBase{
 			ManagedResource: models.NewManagedResource(models.ManagedResourceInput{
@@ -134,7 +139,7 @@ func gatheringLineFromUsageBasedChargeForPeriod(charge usagebased.Charge, servic
 			FeatureKey: intent.FeatureKey,
 			UnitConfig: unitConfig,
 
-			Currency:      intent.Currency.GetCode(),
+			Currency:      invoiceCurrency,
 			ServicePeriod: servicePeriod,
 			InvoiceAt:     invoiceAt,
 
diff --git a/openmeter/billing/charges/usagebased/service/lineengine_test.go b/openmeter/billing/charges/usagebased/service/lineengine_test.go
index eebcd48f66..ab10187b3f 100644
--- a/openmeter/billing/charges/usagebased/service/lineengine_test.go
+++ b/openmeter/billing/charges/usagebased/service/lineengine_test.go
@@ -59,7 +59,7 @@ func TestLineEngineSplitGatheringLineKeepsChargeGroupingWithoutChildReferences(t
 			}),
 			ManagedBy:              billing.SystemManagedLine,
 			Engine:                 billing.LineEngineTypeChargeUsageBased,
-			Currency:               currencyx.Code("USD"),
+			Currency:               currencyx.FiatCode("USD"),
 			ServicePeriod:          servicePeriod,
 			InvoiceAt:              servicePeriod.To,
 			Price:                  lo.FromPtr(price),
diff --git a/openmeter/billing/charges/usagebased/service/linemapper.go b/openmeter/billing/charges/usagebased/service/linemapper.go
index ef6164f473..82265a7c55 100644
--- a/openmeter/billing/charges/usagebased/service/linemapper.go
+++ b/openmeter/billing/charges/usagebased/service/linemapper.go
@@ -35,9 +35,7 @@ func intentFromManualCreatedLine(
 		return usagebased.Intent{}, fmt.Errorf("line id is required")
 	}
 
-	currency, err := currencyx.NewCurrencyBuilder(currencyx.CurrencyTypeFiat).
-		WithCode(line.GetCurrency()).
-		Build()
+	currency, err := line.GetCurrency().AsFiatCurrency()
 	if err != nil {
 		return usagebased.Intent{}, fmt.Errorf("resolving fiat currency %q: %w", line.GetCurrency(), err)
 	}
@@ -133,9 +131,7 @@ func populateStandardLineFromRun(stdLine *billing.StandardLine, input populateSt
 		stdLine.UsageBased = &billing.UsageBasedLine{}
 	}
 
-	cur, err := currencyx.NewCurrencyBuilder(currencyx.CurrencyTypeFiat).
-		WithCode(stdLine.Currency).
-		Build()
+	cur, err := stdLine.Currency.AsFiatCurrency()
 	if err != nil {
 		return fmt.Errorf("creating currency calculator: %w", err)
 	}
diff --git a/openmeter/billing/charges/usagebased/service/linemapper_test.go b/openmeter/billing/charges/usagebased/service/linemapper_test.go
index 2cf92137b9..e864458f3f 100644
--- a/openmeter/billing/charges/usagebased/service/linemapper_test.go
+++ b/openmeter/billing/charges/usagebased/service/linemapper_test.go
@@ -234,7 +234,7 @@ func newUsageBasedStandardLineForTest(period timeutil.ClosedPeriod) *billing.Sta
 			ManagedBy: billing.SystemManagedLine,
 			Engine:    billing.LineEngineTypeChargeUsageBased,
 			InvoiceID: "invoice-id",
-			Currency:  currencyx.Code("USD"),
+			Currency:  currencyx.FiatCode("USD"),
 			Period:    period,
 			InvoiceAt: period.To,
 			ChargeID:  lo.ToPtr("charge-id"),
diff --git a/openmeter/billing/charges/usagebased/service/run/payment_test.go b/openmeter/billing/charges/usagebased/service/run/payment_test.go
index 62b2c344a5..8f1740d005 100644
--- a/openmeter/billing/charges/usagebased/service/run/payment_test.go
+++ b/openmeter/billing/charges/usagebased/service/run/payment_test.go
@@ -117,7 +117,7 @@ func newBookPaymentAuthorizedInput(t testing.TB) BookInvoicedPaymentAuthorizedIn
 					Name:            "line-1",
 				},
 				ManagedBy: billing.SystemManagedLine,
-				Currency:  currencyx.Code("USD"),
+				Currency:  currencyx.FiatCode("USD"),
 				InvoiceID: "invoice-1",
 				InvoiceAt: now,
 				Period: timeutil.ClosedPeriod{
diff --git a/openmeter/billing/gatheringinvoice.go b/openmeter/billing/gatheringinvoice.go
index 33acdb00da..55ce5e0898 100644
--- a/openmeter/billing/gatheringinvoice.go
+++ b/openmeter/billing/gatheringinvoice.go
@@ -30,7 +30,7 @@ type GatheringInvoiceBase struct {
 
 	Number        string                `json:"number"`
 	CustomerID    string                `json:"customerID"`
-	Currency      currencyx.Code        `json:"currency"`
+	Currency      currencyx.FiatCode    `json:"currency"`
 	ServicePeriod timeutil.ClosedPeriod `json:"servicePeriod"`
 
 	NextCollectionAt *time.Time `json:"nextCollectionAt,omitempty"`
@@ -414,7 +414,7 @@ type GatheringLineBase struct {
 	Engine      LineEngineType       `json:"engine,omitempty"`
 	InvoiceID   string               `json:"invoiceID"`
 
-	Currency      currencyx.Code        `json:"currency"`
+	Currency      currencyx.FiatCode    `json:"currency"`
 	ServicePeriod timeutil.ClosedPeriod `json:"period"`
 	InvoiceAt     time.Time             `json:"invoiceAt"`
 	Price         productcatalog.Price  `json:"price"`
@@ -453,7 +453,7 @@ func (i GatheringLineBase) GetTaxConfig() *TaxConfig {
 	return FromProductCatalog(i.TaxConfig)
 }
 
-func (i GatheringLineBase) GetCurrency() currencyx.Code {
+func (i GatheringLineBase) GetCurrency() currencyx.FiatCode {
 	return i.Currency
 }
 
@@ -883,7 +883,7 @@ func (g GatheringLine) AsNewStandardLine(invoiceID string) (*StandardLine, error
 
 type CreatePendingInvoiceLinesInput struct {
 	Customer customer.CustomerID `json:"customer"`
-	Currency currencyx.Code      `json:"currency"`
+	Currency currencyx.FiatCode  `json:"currency"`
 
 	Lines []GatheringLine `json:"lines"`
 }
@@ -928,7 +928,7 @@ type CreatePendingInvoiceLinesResult struct {
 type CreateGatheringInvoiceAdapterInput struct {
 	Namespace string
 	Number    string
-	Currency  currencyx.Code
+	Currency  currencyx.FiatCode
 	Metadata  map[string]string
 
 	Description      *string
@@ -976,7 +976,7 @@ type ListGatheringInvoicesInput struct {
 	ExcludedNamespaces []string
 	IDs                []string
 	Customers          []string
-	Currencies         []currencyx.Code
+	Currencies         []currencyx.FiatCode
 	OrderBy            api.InvoiceOrderBy
 	Order              sortx.Order
 	IncludeDeleted     bool
@@ -1094,5 +1094,5 @@ func (i UpdateGatheringInvoiceInput) Validate() error {
 type PrepareBillableLinesInput = InvoicePendingLinesInput
 
 type PrepareBillableLinesResult struct {
-	LinesByCurrency map[currencyx.Code]GatheringLines
+	LinesByCurrency map[currencyx.FiatCode]GatheringLines
 }
diff --git a/openmeter/billing/httpdriver/invoice.go b/openmeter/billing/httpdriver/invoice.go
index fba33cebb1..4fe0097e94 100644
--- a/openmeter/billing/httpdriver/invoice.go
+++ b/openmeter/billing/httpdriver/invoice.go
@@ -463,7 +463,7 @@ func (h *handler) SimulateInvoice() SimulateInvoiceHandler {
 				CustomerID: &params.CustomerID,
 
 				Number:   body.Number,
-				Currency: currencyx.Code(body.Currency),
+				Currency: currencyx.FiatCode(body.Currency),
 				Lines:    billing.NewStandardInvoiceLines(lines),
 			}, nil
 		},
diff --git a/openmeter/billing/httpdriver/invoice_test.go b/openmeter/billing/httpdriver/invoice_test.go
index 0fdfeb1b6d..49b4a011d1 100644
--- a/openmeter/billing/httpdriver/invoice_test.go
+++ b/openmeter/billing/httpdriver/invoice_test.go
@@ -218,7 +218,7 @@ func (s *InvoicingTestSuite) TestGatheringInvoiceSerialization() {
 	// Let's provision a gathering invoice with a single flat fee line
 	res, err := s.BillingService.CreatePendingInvoiceLines(ctx, billing.CreatePendingInvoiceLinesInput{
 		Customer: cust.GetID(),
-		Currency: currencyx.Code(currency.USD),
+		Currency: currencyx.FiatCode(currency.USD),
 		Lines: []billing.GatheringLine{
 			billing.NewFlatFeeGatheringLine(
 				billing.NewFlatFeeLineInput{
diff --git a/openmeter/billing/httpdriver/invoiceline.go b/openmeter/billing/httpdriver/invoiceline.go
index 4df1ab90cb..00944df1b5 100644
--- a/openmeter/billing/httpdriver/invoiceline.go
+++ b/openmeter/billing/httpdriver/invoiceline.go
@@ -79,7 +79,7 @@ func (h *handler) CreatePendingLine() CreatePendingLineHandler {
 					Namespace: ns,
 					ID:        params.CustomerID,
 				},
-				Currency: currencyx.Code(req.Currency),
+				Currency: currencyx.FiatCode(req.Currency),
 				Lines:    lineEntities,
 			}, nil
 		},
@@ -259,7 +259,7 @@ func mapTaxConfigToAPI(to *productcatalog.TaxConfig) *api.TaxConfig {
 	return lo.ToPtr(productcataloghttp.FromTaxConfig(*to))
 }
 
-func mapDetailedLinesToAPI(lines billing.DetailedLines, currency currencyx.Code, invoiceAt time.Time, taxConfig *productcatalog.TaxConfig) (*[]api.InvoiceDetailedLine, error) {
+func mapDetailedLinesToAPI(lines billing.DetailedLines, currency currencyx.FiatCode, invoiceAt time.Time, taxConfig *productcatalog.TaxConfig) (*[]api.InvoiceDetailedLine, error) {
 	mappedLines, err := slicesx.MapWithErr(lines, func(line billing.DetailedLine) (api.InvoiceDetailedLine, error) {
 		return mapDetailedLineToAPI(line, currency, invoiceAt, taxConfig)
 	})
@@ -270,7 +270,7 @@ func mapDetailedLinesToAPI(lines billing.DetailedLines, currency currencyx.Code,
 	return lo.ToPtr(mappedLines), nil
 }
 
-func mapDetailedLineToAPI(line billing.DetailedLine, currency currencyx.Code, invoiceAt time.Time, taxConfig *productcatalog.TaxConfig) (api.InvoiceDetailedLine, error) {
+func mapDetailedLineToAPI(line billing.DetailedLine, currency currencyx.FiatCode, invoiceAt time.Time, taxConfig *productcatalog.TaxConfig) (api.InvoiceDetailedLine, error) {
 	amountDiscountsAPI, err := mapInvoiceLineAmountDiscountsToAPI(line.AmountDiscounts)
 	if err != nil {
 		return api.InvoiceDetailedLine{}, fmt.Errorf("failed to map amount discounts: %w", err)
diff --git a/openmeter/billing/invoiceline.go b/openmeter/billing/invoiceline.go
index 95dc569164..2d8f5f1be1 100644
--- a/openmeter/billing/invoiceline.go
+++ b/openmeter/billing/invoiceline.go
@@ -103,7 +103,7 @@ type GenericInvoiceLineReader interface {
 	GetInvoiceID() string
 	GetEngine() LineEngineType
 	GetLineEngineType() LineEngineType
-	GetCurrency() currencyx.Code
+	GetCurrency() currencyx.FiatCode
 	GetPrice() *productcatalog.Price
 	GetUnitConfig() *productcatalog.UnitConfig
 	GetTaxConfig() *TaxConfig
diff --git a/openmeter/billing/invoicelinesplitgroup.go b/openmeter/billing/invoicelinesplitgroup.go
index 028eb452f0..c60b95bdb7 100644
--- a/openmeter/billing/invoicelinesplitgroup.go
+++ b/openmeter/billing/invoicelinesplitgroup.go
@@ -59,7 +59,7 @@ type SplitLineGroupCreate struct {
 	Price             *productcatalog.Price  `json:"price"`
 	FeatureKey        *string                `json:"featureKey,omitempty"`
 	Subscription      *SubscriptionReference `json:"subscription,omitempty"`
-	Currency          currencyx.Code         `json:"currency"`
+	Currency          currencyx.FiatCode     `json:"currency"`
 	UniqueReferenceID *string                `json:"childUniqueReferenceId,omitempty"`
 }
 
@@ -127,7 +127,7 @@ type SplitLineGroup struct {
 	Price             *productcatalog.Price  `json:"price"`
 	FeatureKey        *string                `json:"featureKey,omitempty"`
 	Subscription      *SubscriptionReference `json:"subscription,omitempty"`
-	Currency          currencyx.Code         `json:"currency"`
+	Currency          currencyx.FiatCode     `json:"currency"`
 	UniqueReferenceID *string                `json:"childUniqueReferenceId,omitempty"`
 }
 
diff --git a/openmeter/billing/sequence/sequence.go b/openmeter/billing/sequence/sequence.go
index d94e02d6b0..bfc258075b 100644
--- a/openmeter/billing/sequence/sequence.go
+++ b/openmeter/billing/sequence/sequence.go
@@ -98,7 +98,7 @@ var (
 type GenerationInput struct {
 	Namespace    string
 	CustomerName string
-	Currency     currencyx.Code
+	Currency     currencyx.FiatCode
 }
 
 func (i GenerationInput) Validate() error {
diff --git a/openmeter/billing/sequence/service/service.go b/openmeter/billing/sequence/service/service.go
index 764906ff01..0c7e514f06 100644
--- a/openmeter/billing/sequence/service/service.go
+++ b/openmeter/billing/sequence/service/service.go
@@ -68,7 +68,7 @@ func New(config Config) (*Service, error) {
 
 type sequenceInput struct {
 	CustomerPrefix     string
-	Currency           currencyx.Code
+	Currency           currencyx.FiatCode
 	NextSequenceNumber string
 }
 
diff --git a/openmeter/billing/sequence/service/service_test.go b/openmeter/billing/sequence/service/service_test.go
index 382f18466f..67d94eb1eb 100644
--- a/openmeter/billing/sequence/service/service_test.go
+++ b/openmeter/billing/sequence/service/service_test.go
@@ -222,7 +222,7 @@ func (s *SequenceServiceSuite) generateInvoiceNumber(ctx context.Context, namesp
 	return s.service.GenerateInvoiceSequenceNumber(ctx, sequence.GenerationInput{
 		Namespace:    namespace,
 		CustomerName: "Acme Inc",
-		Currency:     currencyx.Code("USD"),
+		Currency:     currencyx.FiatCode("USD"),
 	}, sequence.Definition{
 		Prefix:         "INV",
 		SuffixTemplate: "{{.CustomerPrefix}}-{{.NextSequenceNumber}}",
diff --git a/openmeter/billing/service/gatheringinvoicependinglines.go b/openmeter/billing/service/gatheringinvoicependinglines.go
index 9f2f76246a..ef66d16f79 100644
--- a/openmeter/billing/service/gatheringinvoicependinglines.go
+++ b/openmeter/billing/service/gatheringinvoicependinglines.go
@@ -167,7 +167,7 @@ func (s *Service) prepareBillableLines(ctx context.Context, input billing.Prepar
 				}
 			}
 
-			invoicesByCurrency := lo.SliceToMap(existingGatheringInvoices.Items, func(i billing.GatheringInvoice) (currencyx.Code, gatheringInvoiceWithFeatureMeters) {
+			invoicesByCurrency := lo.SliceToMap(existingGatheringInvoices.Items, func(i billing.GatheringInvoice) (currencyx.FiatCode, gatheringInvoiceWithFeatureMeters) {
 				return i.Currency, gatheringInvoiceWithFeatureMeters{
 					Invoice: i,
 				}
@@ -199,7 +199,7 @@ func (s *Service) prepareBillableLines(ctx context.Context, input billing.Prepar
 				return nil, err
 			}
 
-			linesToBeBilledByCurrency := make(map[currencyx.Code]billing.GatheringLines)
+			linesToBeBilledByCurrency := make(map[currencyx.FiatCode]billing.GatheringLines)
 
 			for currency, inScopeLines := range inScopeLinesByCurrency {
 				// Let's first make sure we have properly split the progressively billed
@@ -311,7 +311,7 @@ type gatheringInvoiceWithFeatureMeters struct {
 }
 
 type gatherInScopeLineInput struct {
-	GatheringInvoicesByCurrency map[currencyx.Code]gatheringInvoiceWithFeatureMeters
+	GatheringInvoicesByCurrency map[currencyx.FiatCode]gatheringInvoiceWithFeatureMeters
 	// If set restricts the lines to be included to these IDs, otherwise the AsOf is used
 	// to determine the lines to be included.
 	LinesToInclude     mo.Option[[]string]
@@ -319,7 +319,7 @@ type gatherInScopeLineInput struct {
 	ProgressiveBilling bool
 }
 
-type gatherInScopeLinesResult map[currencyx.Code][]gatheringLineWithBillablePeriod
+type gatherInScopeLinesResult map[currencyx.FiatCode][]gatheringLineWithBillablePeriod
 
 func (s *Service) gatherInScopeLines(ctx context.Context, in gatherInScopeLineInput) (gatherInScopeLinesResult, error) {
 	res := make(gatherInScopeLinesResult)
@@ -496,7 +496,7 @@ func (s *Service) hasInvoicableLines(ctx context.Context, in hasInvoicableLinesI
 	}
 
 	inScopeLines, err := s.gatherInScopeLines(ctx, gatherInScopeLineInput{
-		GatheringInvoicesByCurrency: map[currencyx.Code]gatheringInvoiceWithFeatureMeters{
+		GatheringInvoicesByCurrency: map[currencyx.FiatCode]gatheringInvoiceWithFeatureMeters{
 			in.Invoice.Currency: {
 				Invoice:       in.Invoice,
 				FeatureMeters: in.FeatureMeters,
diff --git a/openmeter/billing/service/invoicecalc/collectionat_test.go b/openmeter/billing/service/invoicecalc/collectionat_test.go
index 7141142e0d..0d9f8785da 100644
--- a/openmeter/billing/service/invoicecalc/collectionat_test.go
+++ b/openmeter/billing/service/invoicecalc/collectionat_test.go
@@ -379,7 +379,7 @@ func newStandardLine(t *testing.T, invoiceAt string) *billing.StandardLine {
 	return &billing.StandardLine{
 		StandardLineBase: billing.StandardLineBase{
 			ManagedResource: billing.GatheringLineBase{}.ManagedResource,
-			Currency:        currencyx.Code("USD"),
+			Currency:        currencyx.FiatCode("USD"),
 			ManagedBy:       billing.ManuallyManagedLine,
 			InvoiceAt:       at,
 			Period: timeutil.ClosedPeriod{
@@ -427,7 +427,7 @@ func newFlatFeeStandardLine(t *testing.T, invoiceAt string) *billing.StandardLin
 			To:   at,
 		},
 		Name:      "Flat fee",
-		Currency:  currencyx.Code("USD"),
+		Currency:  currencyx.FiatCode("USD"),
 		ManagedBy: billing.ManuallyManagedLine,
 
 		PerUnitAmount: alpacadecimal.NewFromFloat(10),
diff --git a/openmeter/billing/service/invoiceupdate.go b/openmeter/billing/service/invoiceupdate.go
index 3b3a327e30..9c53590c78 100644
--- a/openmeter/billing/service/invoiceupdate.go
+++ b/openmeter/billing/service/invoiceupdate.go
@@ -746,7 +746,7 @@ func (s *Service) taxCodeIDWithBackfill(ctx context.Context, namespace string, t
 
 type preallocatedCreatedStandardLinesInput struct {
 	Invoice      billing.InvoiceID
-	Currency     currencyx.Code
+	Currency     currencyx.FiatCode
 	SchemaLevel  int
 	CreatedLines []billing.GenericInvoiceLine
 }
diff --git a/openmeter/billing/service/invoiceupdate_test.go b/openmeter/billing/service/invoiceupdate_test.go
index a0e7f129ce..63116a48cf 100644
--- a/openmeter/billing/service/invoiceupdate_test.go
+++ b/openmeter/billing/service/invoiceupdate_test.go
@@ -765,7 +765,7 @@ func TestApplyManualInvoiceLineOverridesMarksGatheringManualChanges(t *testing.T
 				ID:              "invoice-1",
 				Name:            "invoice-1",
 			},
-			Currency:      currencyx.Code("USD"),
+			Currency:      currencyx.FiatCode("USD"),
 			ServicePeriod: originalLine.ServicePeriod,
 			SchemaLevel:   1,
 		},
@@ -815,7 +815,7 @@ func newStandardLineForLineEngineTest(id string, engine billing.LineEngineType,
 			},
 			Engine:    engine,
 			InvoiceID: "invoice-1",
-			Currency:  currencyx.Code("USD"),
+			Currency:  currencyx.FiatCode("USD"),
 			ManagedBy: billing.ManuallyManagedLine,
 			Period: timeutil.ClosedPeriod{
 				From: now,
@@ -855,7 +855,7 @@ func newGatheringLineForLineEngineTest(id string, engine billing.LineEngineType,
 			},
 			Engine:    engine,
 			InvoiceID: "invoice-1",
-			Currency:  currencyx.Code("USD"),
+			Currency:  currencyx.FiatCode("USD"),
 			ManagedBy: billing.ManuallyManagedLine,
 			ServicePeriod: timeutil.ClosedPeriod{
 				From: now,
diff --git a/openmeter/billing/service/stdinvoiceline.go b/openmeter/billing/service/stdinvoiceline.go
index 2c68cb5ca4..487b804430 100644
--- a/openmeter/billing/service/stdinvoiceline.go
+++ b/openmeter/billing/service/stdinvoiceline.go
@@ -173,7 +173,7 @@ type upsertGatheringInvoiceForCurrencyResponse struct {
 	IsInvoiceNew bool
 }
 
-func (s *Service) upsertGatheringInvoiceForCurrency(ctx context.Context, currency currencyx.Code, customerProfile billing.CustomerOverrideWithDetails) (*upsertGatheringInvoiceForCurrencyResponse, error) {
+func (s *Service) upsertGatheringInvoiceForCurrency(ctx context.Context, currency currencyx.FiatCode, customerProfile billing.CustomerOverrideWithDetails) (*upsertGatheringInvoiceForCurrencyResponse, error) {
 	// We would want to stage a pending invoice Line
 	pendingInvoiceList, err := s.adapter.ListGatheringInvoices(ctx, billing.ListGatheringInvoicesInput{
 		Page: pagination.Page{
@@ -182,7 +182,7 @@ func (s *Service) upsertGatheringInvoiceForCurrency(ctx context.Context, currenc
 		},
 		Customers:      []string{customerProfile.Customer.ID},
 		Namespaces:     []string{customerProfile.Customer.Namespace},
-		Currencies:     []currencyx.Code{currency},
+		Currencies:     []currencyx.FiatCode{currency},
 		OrderBy:        api.InvoiceOrderByCreatedAt,
 		Order:          sortx.OrderAsc,
 		IncludeDeleted: true,
diff --git a/openmeter/billing/stdinvoice.go b/openmeter/billing/stdinvoice.go
index 148e3417b7..ed3826d56e 100644
--- a/openmeter/billing/stdinvoice.go
+++ b/openmeter/billing/stdinvoice.go
@@ -248,7 +248,7 @@ type StandardInvoiceBase struct {
 
 	Metadata map[string]string `json:"metadata"`
 
-	Currency      currencyx.Code               `json:"currency,omitempty"`
+	Currency      currencyx.FiatCode           `json:"currency,omitempty"`
 	Status        StandardInvoiceStatus        `json:"status"`
 	StatusDetails StandardInvoiceStatusDetails `json:"statusDetail,omitempty"`
 
@@ -743,7 +743,7 @@ type CreateInvoiceAdapterInput struct {
 	Customer  customer.Customer
 	Profile   Profile
 	Number    string
-	Currency  currencyx.Code
+	Currency  currencyx.FiatCode
 	Status    StandardInvoiceStatus
 	Metadata  map[string]string
 	IssuedAt  time.Time
@@ -927,7 +927,7 @@ type SimulateInvoiceInput struct {
 	Customer   *customer.Customer
 
 	Number   *string
-	Currency currencyx.Code
+	Currency currencyx.FiatCode
 	Lines    StandardInvoiceLines
 }
 
@@ -1208,7 +1208,7 @@ type ListStandardInvoicesResponse = pagination.Result[StandardInvoice]
 
 type CreateStandardInvoiceFromGatheringLinesInput struct {
 	Customer    customer.CustomerID
-	Currency    currencyx.Code
+	Currency    currencyx.FiatCode
 	Description *string
 
 	Lines                       GatheringLines
diff --git a/openmeter/billing/stdinvoiceline.go b/openmeter/billing/stdinvoiceline.go
index 348c3b080c..686d94fa05 100644
--- a/openmeter/billing/stdinvoiceline.go
+++ b/openmeter/billing/stdinvoiceline.go
@@ -30,8 +30,8 @@ type StandardLineBase struct {
 	ManagedBy   InvoiceLineManagedBy `json:"managedBy"`
 	Engine      LineEngineType       `json:"engine,omitempty"`
 
-	InvoiceID string         `json:"invoiceID,omitempty"`
-	Currency  currencyx.Code `json:"currency"`
+	InvoiceID string             `json:"invoiceID,omitempty"`
+	Currency  currencyx.FiatCode `json:"currency"`
 
 	// Lifecycle
 	Period timeutil.ClosedPeriod `json:"period"`
@@ -184,16 +184,14 @@ func (i StandardLineBase) GetCreditsApplied() CreditsApplied {
 	return i.CreditsApplied
 }
 
-func (i StandardLineBase) GetCurrency() currencyx.Code {
+func (i StandardLineBase) GetCurrency() currencyx.FiatCode {
 	return i.Currency
 }
 
 func (i StandardLineBase) GetCurrencyCalculator() (currencyx.Currency, error) {
-	currency, err := currencyx.NewCurrencyBuilder(currencyx.CurrencyTypeFiat).
-		WithCode(i.Currency).
-		Build()
+	currency, err := i.Currency.AsFiatCurrency()
 	if err != nil {
-		return nil, fmt.Errorf("building fiat currency calculator: %w", err)
+		return nil, fmt.Errorf("resolving fiat currency calculator: %w", err)
 	}
 
 	return currency, nil
@@ -852,7 +850,7 @@ type NewFlatFeeLineInput struct {
 	Annotations models.Annotations
 	Description *string
 
-	Currency currencyx.Code
+	Currency currencyx.FiatCode
 
 	ManagedBy InvoiceLineManagedBy
 
diff --git a/openmeter/billing/stdinvoiceline_test.go b/openmeter/billing/stdinvoiceline_test.go
index 15c63ead02..4bdb6d8251 100644
--- a/openmeter/billing/stdinvoiceline_test.go
+++ b/openmeter/billing/stdinvoiceline_test.go
@@ -114,7 +114,7 @@ func validStandardLineForValidation() StandardLine {
 			},
 			ManagedBy: SystemManagedLine,
 			InvoiceID: "inv_123",
-			Currency:  currencyx.Code("USD"),
+			Currency:  currencyx.FiatCode("USD"),
 			Period: timeutil.ClosedPeriod{
 				From: start,
 				To:   start.Add(time.Hour),
diff --git a/openmeter/billing/worker/subscriptionsync/service/reconciler/invoiceupdater/invoiceupdate.go b/openmeter/billing/worker/subscriptionsync/service/reconciler/invoiceupdater/invoiceupdate.go
index cc4aa82fcb..db4176d1d6 100644
--- a/openmeter/billing/worker/subscriptionsync/service/reconciler/invoiceupdater/invoiceupdate.go
+++ b/openmeter/billing/worker/subscriptionsync/service/reconciler/invoiceupdater/invoiceupdate.go
@@ -276,7 +276,7 @@ func (u *Updater) provisionUpcomingLines(ctx context.Context, customerID custome
 		return nil
 	}
 
-	linesByCurrency := lo.GroupBy(lines, func(l billing.GatheringLine) currencyx.Code {
+	linesByCurrency := lo.GroupBy(lines, func(l billing.GatheringLine) currencyx.FiatCode {
 		return l.Currency
 	})
 
diff --git a/openmeter/billing/worker/subscriptionsync/service/targetstate/targetstateitem.go b/openmeter/billing/worker/subscriptionsync/service/targetstate/targetstateitem.go
index 522a2b866b..6f7d42fb37 100644
--- a/openmeter/billing/worker/subscriptionsync/service/targetstate/targetstateitem.go
+++ b/openmeter/billing/worker/subscriptionsync/service/targetstate/targetstateitem.go
@@ -11,6 +11,7 @@ import (
 	"github.com/openmeterio/openmeter/openmeter/currencies"
 	"github.com/openmeterio/openmeter/openmeter/productcatalog"
 	"github.com/openmeterio/openmeter/openmeter/subscription"
+	"github.com/openmeterio/openmeter/pkg/currencyx"
 	"github.com/openmeterio/openmeter/pkg/models"
 	"github.com/openmeterio/openmeter/pkg/timeutil"
 )
@@ -50,6 +51,10 @@ func (r StateItem) GetServicePeriod() timeutil.ClosedPeriod {
 }
 
 func (r StateItem) GetExpectedLine() (*billing.GatheringLine, error) {
+	if !r.Currency.IsFiat() {
+		return nil, fmt.Errorf("billing line currency must be fiat: %s", r.Currency.GetCode())
+	}
+
 	line := billing.GatheringLine{
 		GatheringLineBase: billing.GatheringLineBase{
 			ManagedResource: models.NewManagedResource(models.ManagedResourceInput{
@@ -58,7 +63,7 @@ func (r StateItem) GetExpectedLine() (*billing.GatheringLine, error) {
 				Description: r.Spec.RateCard.AsMeta().Description,
 			}),
 			ManagedBy:              billing.SubscriptionManagedLine,
-			Currency:               r.Currency.GetCode(),
+			Currency:               currencyx.FiatCode(r.Currency.GetCode()),
 			ChildUniqueReferenceID: &r.UniqueID,
 			TaxConfig:              r.Spec.RateCard.AsMeta().TaxConfig,
 			ServicePeriod:          r.GetServicePeriod(),
diff --git a/openmeter/ent/db/billinggatheringinvoiceline.go b/openmeter/ent/db/billinggatheringinvoiceline.go
index d165ecd7de..c60c9cf60e 100644
--- a/openmeter/ent/db/billinggatheringinvoiceline.go
+++ b/openmeter/ent/db/billinggatheringinvoiceline.go
@@ -46,7 +46,7 @@ type BillingGatheringInvoiceLine struct {
 	// Description holds the value of the "description" field.
 	Description *string `json:"description,omitempty"`
 	// Currency holds the value of the "currency" field.
-	Currency currencyx.Code `json:"currency,omitempty"`
+	Currency currencyx.FiatCode `json:"currency,omitempty"`
 	// ServicePeriodStart holds the value of the "service_period_start" field.
 	ServicePeriodStart time.Time `json:"service_period_start,omitempty"`
 	// ServicePeriodEnd holds the value of the "service_period_end" field.
@@ -291,7 +291,7 @@ func (_m *BillingGatheringInvoiceLine) assignValues(columns []string, values []a
 			if value, ok := values[i].(*sql.NullString); !ok {
 				return fmt.Errorf("unexpected type %T for field currency", values[i])
 			} else if value.Valid {
-				_m.Currency = currencyx.Code(value.String)
+				_m.Currency = currencyx.FiatCode(value.String)
 			}
 		case billinggatheringinvoiceline.FieldServicePeriodStart:
 			if value, ok := values[i].(*sql.NullTime); !ok {
diff --git a/openmeter/ent/db/billinggatheringinvoiceline/where.go b/openmeter/ent/db/billinggatheringinvoiceline/where.go
index 241e525f89..44c32ed9e6 100644
--- a/openmeter/ent/db/billinggatheringinvoiceline/where.go
+++ b/openmeter/ent/db/billinggatheringinvoiceline/where.go
@@ -99,7 +99,7 @@ func Description(v string) predicate.BillingGatheringInvoiceLine {
 }
 
 // Currency applies equality check predicate on the "currency" field. It's identical to CurrencyEQ.
-func Currency(v currencyx.Code) predicate.BillingGatheringInvoiceLine {
+func Currency(v currencyx.FiatCode) predicate.BillingGatheringInvoiceLine {
 	vc := string(v)
 	return predicate.BillingGatheringInvoiceLine(sql.FieldEQ(FieldCurrency, vc))
 }
@@ -530,19 +530,19 @@ func DescriptionContainsFold(v string) predicate.BillingGatheringInvoiceLine {
 }
 
 // CurrencyEQ applies the EQ predicate on the "currency" field.
-func CurrencyEQ(v currencyx.Code) predicate.BillingGatheringInvoiceLine {
+func CurrencyEQ(v currencyx.FiatCode) predicate.BillingGatheringInvoiceLine {
 	vc := string(v)
 	return predicate.BillingGatheringInvoiceLine(sql.FieldEQ(FieldCurrency, vc))
 }
 
 // CurrencyNEQ applies the NEQ predicate on the "currency" field.
-func CurrencyNEQ(v currencyx.Code) predicate.BillingGatheringInvoiceLine {
+func CurrencyNEQ(v currencyx.FiatCode) predicate.BillingGatheringInvoiceLine {
 	vc := string(v)
 	return predicate.BillingGatheringInvoiceLine(sql.FieldNEQ(FieldCurrency, vc))
 }
 
 // CurrencyIn applies the In predicate on the "currency" field.
-func CurrencyIn(vs ...currencyx.Code) predicate.BillingGatheringInvoiceLine {
+func CurrencyIn(vs ...currencyx.FiatCode) predicate.BillingGatheringInvoiceLine {
 	v := make([]any, len(vs))
 	for i := range v {
 		v[i] = string(vs[i])
@@ -551,7 +551,7 @@ func CurrencyIn(vs ...currencyx.Code) predicate.BillingGatheringInvoiceLine {
 }
 
 // CurrencyNotIn applies the NotIn predicate on the "currency" field.
-func CurrencyNotIn(vs ...currencyx.Code) predicate.BillingGatheringInvoiceLine {
+func CurrencyNotIn(vs ...currencyx.FiatCode) predicate.BillingGatheringInvoiceLine {
 	v := make([]any, len(vs))
 	for i := range v {
 		v[i] = string(vs[i])
@@ -560,55 +560,55 @@ func CurrencyNotIn(vs ...currencyx.Code) predicate.BillingGatheringInvoiceLine {
 }
 
 // CurrencyGT applies the GT predicate on the "currency" field.
-func CurrencyGT(v currencyx.Code) predicate.BillingGatheringInvoiceLine {
+func CurrencyGT(v currencyx.FiatCode) predicate.BillingGatheringInvoiceLine {
 	vc := string(v)
 	return predicate.BillingGatheringInvoiceLine(sql.FieldGT(FieldCurrency, vc))
 }
 
 // CurrencyGTE applies the GTE predicate on the "currency" field.
-func CurrencyGTE(v currencyx.Code) predicate.BillingGatheringInvoiceLine {
+func CurrencyGTE(v currencyx.FiatCode) predicate.BillingGatheringInvoiceLine {
 	vc := string(v)
 	return predicate.BillingGatheringInvoiceLine(sql.FieldGTE(FieldCurrency, vc))
 }
 
 // CurrencyLT applies the LT predicate on the "currency" field.
-func CurrencyLT(v currencyx.Code) predicate.BillingGatheringInvoiceLine {
+func CurrencyLT(v currencyx.FiatCode) predicate.BillingGatheringInvoiceLine {
 	vc := string(v)
 	return predicate.BillingGatheringInvoiceLine(sql.FieldLT(FieldCurrency, vc))
 }
 
 // CurrencyLTE applies the LTE predicate on the "currency" field.
-func CurrencyLTE(v currencyx.Code) predicate.BillingGatheringInvoiceLine {
+func CurrencyLTE(v currencyx.FiatCode) predicate.BillingGatheringInvoiceLine {
 	vc := string(v)
 	return predicate.BillingGatheringInvoiceLine(sql.FieldLTE(FieldCurrency, vc))
 }
 
 // CurrencyContains applies the Contains predicate on the "currency" field.
-func CurrencyContains(v currencyx.Code) predicate.BillingGatheringInvoiceLine {
+func CurrencyContains(v currencyx.FiatCode) predicate.BillingGatheringInvoiceLine {
 	vc := string(v)
 	return predicate.BillingGatheringInvoiceLine(sql.FieldContains(FieldCurrency, vc))
 }
 
 // CurrencyHasPrefix applies the HasPrefix predicate on the "currency" field.
-func CurrencyHasPrefix(v currencyx.Code) predicate.BillingGatheringInvoiceLine {
+func CurrencyHasPrefix(v currencyx.FiatCode) predicate.BillingGatheringInvoiceLine {
 	vc := string(v)
 	return predicate.BillingGatheringInvoiceLine(sql.FieldHasPrefix(FieldCurrency, vc))
 }
 
 // CurrencyHasSuffix applies the HasSuffix predicate on the "currency" field.
-func CurrencyHasSuffix(v currencyx.Code) predicate.BillingGatheringInvoiceLine {
+func CurrencyHasSuffix(v currencyx.FiatCode) predicate.BillingGatheringInvoiceLine {
 	vc := string(v)
 	return predicate.BillingGatheringInvoiceLine(sql.FieldHasSuffix(FieldCurrency, vc))
 }
 
 // CurrencyEqualFold applies the EqualFold predicate on the "currency" field.
-func CurrencyEqualFold(v currencyx.Code) predicate.BillingGatheringInvoiceLine {
+func CurrencyEqualFold(v currencyx.FiatCode) predicate.BillingGatheringInvoiceLine {
 	vc := string(v)
 	return predicate.BillingGatheringInvoiceLine(sql.FieldEqualFold(FieldCurrency, vc))
 }
 
 // CurrencyContainsFold applies the ContainsFold predicate on the "currency" field.
-func CurrencyContainsFold(v currencyx.Code) predicate.BillingGatheringInvoiceLine {
+func CurrencyContainsFold(v currencyx.FiatCode) predicate.BillingGatheringInvoiceLine {
 	vc := string(v)
 	return predicate.BillingGatheringInvoiceLine(sql.FieldContainsFold(FieldCurrency, vc))
 }
diff --git a/openmeter/ent/db/billinggatheringinvoiceline_create.go b/openmeter/ent/db/billinggatheringinvoiceline_create.go
index 64435f6812..e263476464 100644
--- a/openmeter/ent/db/billinggatheringinvoiceline_create.go
+++ b/openmeter/ent/db/billinggatheringinvoiceline_create.go
@@ -115,7 +115,7 @@ func (_c *BillingGatheringInvoiceLineCreate) SetNillableDescription(v *string) *
 }
 
 // SetCurrency sets the "currency" field.
-func (_c *BillingGatheringInvoiceLineCreate) SetCurrency(v currencyx.Code) *BillingGatheringInvoiceLineCreate {
+func (_c *BillingGatheringInvoiceLineCreate) SetCurrency(v currencyx.FiatCode) *BillingGatheringInvoiceLineCreate {
 	_c.mutation.SetCurrency(v)
 	return _c
 }
diff --git a/openmeter/ent/db/billinginvoice.go b/openmeter/ent/db/billinginvoice.go
index 4f8433abd5..0cc7715b27 100644
--- a/openmeter/ent/db/billinginvoice.go
+++ b/openmeter/ent/db/billinginvoice.go
@@ -119,7 +119,7 @@ type BillingInvoice struct {
 	// DeletionSource holds the value of the "deletion_source" field.
 	DeletionSource *billing.ChangeSource `json:"deletion_source,omitempty"`
 	// Currency holds the value of the "currency" field.
-	Currency currencyx.Code `json:"currency,omitempty"`
+	Currency currencyx.FiatCode `json:"currency,omitempty"`
 	// DueAt holds the value of the "due_at" field.
 	DueAt *time.Time `json:"due_at,omitempty"`
 	// Status holds the value of the "status" field.
@@ -648,7 +648,7 @@ func (_m *BillingInvoice) assignValues(columns []string, values []any) error {
 			if value, ok := values[i].(*sql.NullString); !ok {
 				return fmt.Errorf("unexpected type %T for field currency", values[i])
 			} else if value.Valid {
-				_m.Currency = currencyx.Code(value.String)
+				_m.Currency = currencyx.FiatCode(value.String)
 			}
 		case billinginvoice.FieldDueAt:
 			if value, ok := values[i].(*sql.NullTime); !ok {
diff --git a/openmeter/ent/db/billinginvoice/where.go b/openmeter/ent/db/billinginvoice/where.go
index caf01aa5c9..b1b50065fc 100644
--- a/openmeter/ent/db/billinginvoice/where.go
+++ b/openmeter/ent/db/billinginvoice/where.go
@@ -282,7 +282,7 @@ func QuantitySnapshotedAt(v time.Time) predicate.BillingInvoice {
 }
 
 // Currency applies equality check predicate on the "currency" field. It's identical to CurrencyEQ.
-func Currency(v currencyx.Code) predicate.BillingInvoice {
+func Currency(v currencyx.FiatCode) predicate.BillingInvoice {
 	vc := string(v)
 	return predicate.BillingInvoice(sql.FieldEQ(FieldCurrency, vc))
 }
@@ -3056,19 +3056,19 @@ func DeletionSourceNotNil() predicate.BillingInvoice {
 }
 
 // CurrencyEQ applies the EQ predicate on the "currency" field.
-func CurrencyEQ(v currencyx.Code) predicate.BillingInvoice {
+func CurrencyEQ(v currencyx.FiatCode) predicate.BillingInvoice {
 	vc := string(v)
 	return predicate.BillingInvoice(sql.FieldEQ(FieldCurrency, vc))
 }
 
 // CurrencyNEQ applies the NEQ predicate on the "currency" field.
-func CurrencyNEQ(v currencyx.Code) predicate.BillingInvoice {
+func CurrencyNEQ(v currencyx.FiatCode) predicate.BillingInvoice {
 	vc := string(v)
 	return predicate.BillingInvoice(sql.FieldNEQ(FieldCurrency, vc))
 }
 
 // CurrencyIn applies the In predicate on the "currency" field.
-func CurrencyIn(vs ...currencyx.Code) predicate.BillingInvoice {
+func CurrencyIn(vs ...currencyx.FiatCode) predicate.BillingInvoice {
 	v := make([]any, len(vs))
 	for i := range v {
 		v[i] = string(vs[i])
@@ -3077,7 +3077,7 @@ func CurrencyIn(vs ...currencyx.Code) predicate.BillingInvoice {
 }
 
 // CurrencyNotIn applies the NotIn predicate on the "currency" field.
-func CurrencyNotIn(vs ...currencyx.Code) predicate.BillingInvoice {
+func CurrencyNotIn(vs ...currencyx.FiatCode) predicate.BillingInvoice {
 	v := make([]any, len(vs))
 	for i := range v {
 		v[i] = string(vs[i])
@@ -3086,55 +3086,55 @@ func CurrencyNotIn(vs ...currencyx.Code) predicate.BillingInvoice {
 }
 
 // CurrencyGT applies the GT predicate on the "currency" field.
-func CurrencyGT(v currencyx.Code) predicate.BillingInvoice {
+func CurrencyGT(v currencyx.FiatCode) predicate.BillingInvoice {
 	vc := string(v)
 	return predicate.BillingInvoice(sql.FieldGT(FieldCurrency, vc))
 }
 
 // CurrencyGTE applies the GTE predicate on the "currency" field.
-func CurrencyGTE(v currencyx.Code) predicate.BillingInvoice {
+func CurrencyGTE(v currencyx.FiatCode) predicate.BillingInvoice {
 	vc := string(v)
 	return predicate.BillingInvoice(sql.FieldGTE(FieldCurrency, vc))
 }
 
 // CurrencyLT applies the LT predicate on the "currency" field.
-func CurrencyLT(v currencyx.Code) predicate.BillingInvoice {
+func CurrencyLT(v currencyx.FiatCode) predicate.BillingInvoice {
 	vc := string(v)
 	return predicate.BillingInvoice(sql.FieldLT(FieldCurrency, vc))
 }
 
 // CurrencyLTE applies the LTE predicate on the "currency" field.
-func CurrencyLTE(v currencyx.Code) predicate.BillingInvoice {
+func CurrencyLTE(v currencyx.FiatCode) predicate.BillingInvoice {
 	vc := string(v)
 	return predicate.BillingInvoice(sql.FieldLTE(FieldCurrency, vc))
 }
 
 // CurrencyContains applies the Contains predicate on the "currency" field.
-func CurrencyContains(v currencyx.Code) predicate.BillingInvoice {
+func CurrencyContains(v currencyx.FiatCode) predicate.BillingInvoice {
 	vc := string(v)
 	return predicate.BillingInvoice(sql.FieldContains(FieldCurrency, vc))
 }
 
 // CurrencyHasPrefix applies the HasPrefix predicate on the "currency" field.
-func CurrencyHasPrefix(v currencyx.Code) predicate.BillingInvoice {
+func CurrencyHasPrefix(v currencyx.FiatCode) predicate.BillingInvoice {
 	vc := string(v)
 	return predicate.BillingInvoice(sql.FieldHasPrefix(FieldCurrency, vc))
 }
 
 // CurrencyHasSuffix applies the HasSuffix predicate on the "currency" field.
-func CurrencyHasSuffix(v currencyx.Code) predicate.BillingInvoice {
+func CurrencyHasSuffix(v currencyx.FiatCode) predicate.BillingInvoice {
 	vc := string(v)
 	return predicate.BillingInvoice(sql.FieldHasSuffix(FieldCurrency, vc))
 }
 
 // CurrencyEqualFold applies the EqualFold predicate on the "currency" field.
-func CurrencyEqualFold(v currencyx.Code) predicate.BillingInvoice {
+func CurrencyEqualFold(v currencyx.FiatCode) predicate.BillingInvoice {
 	vc := string(v)
 	return predicate.BillingInvoice(sql.FieldEqualFold(FieldCurrency, vc))
 }
 
 // CurrencyContainsFold applies the ContainsFold predicate on the "currency" field.
-func CurrencyContainsFold(v currencyx.Code) predicate.BillingInvoice {
+func CurrencyContainsFold(v currencyx.FiatCode) predicate.BillingInvoice {
 	vc := string(v)
 	return predicate.BillingInvoice(sql.FieldContainsFold(FieldCurrency, vc))
 }
diff --git a/openmeter/ent/db/billinginvoice_create.go b/openmeter/ent/db/billinginvoice_create.go
index 257f44a82d..6a33745727 100644
--- a/openmeter/ent/db/billinginvoice_create.go
+++ b/openmeter/ent/db/billinginvoice_create.go
@@ -546,7 +546,7 @@ func (_c *BillingInvoiceCreate) SetNillableDeletionSource(v *billing.ChangeSourc
 }
 
 // SetCurrency sets the "currency" field.
-func (_c *BillingInvoiceCreate) SetCurrency(v currencyx.Code) *BillingInvoiceCreate {
+func (_c *BillingInvoiceCreate) SetCurrency(v currencyx.FiatCode) *BillingInvoiceCreate {
 	_c.mutation.SetCurrency(v)
 	return _c
 }
diff --git a/openmeter/ent/db/billinginvoiceline.go b/openmeter/ent/db/billinginvoiceline.go
index 7c25f85850..c56ce3c91f 100644
--- a/openmeter/ent/db/billinginvoiceline.go
+++ b/openmeter/ent/db/billinginvoiceline.go
@@ -54,7 +54,7 @@ type BillingInvoiceLine struct {
 	// Description holds the value of the "description" field.
 	Description *string `json:"description,omitempty"`
 	// Currency holds the value of the "currency" field.
-	Currency currencyx.Code `json:"currency,omitempty"`
+	Currency currencyx.FiatCode `json:"currency,omitempty"`
 	// TaxConfig holds the value of the "tax_config" field.
 	TaxConfig billing.TaxConfig `json:"tax_config,omitempty"`
 	// TaxCodeID holds the value of the "tax_code_id" field.
@@ -475,7 +475,7 @@ func (_m *BillingInvoiceLine) assignValues(columns []string, values []any) error
 			if value, ok := values[i].(*sql.NullString); !ok {
 				return fmt.Errorf("unexpected type %T for field currency", values[i])
 			} else if value.Valid {
-				_m.Currency = currencyx.Code(value.String)
+				_m.Currency = currencyx.FiatCode(value.String)
 			}
 		case billinginvoiceline.FieldTaxConfig:
 			if value, ok := values[i].(*[]byte); !ok {
diff --git a/openmeter/ent/db/billinginvoiceline/where.go b/openmeter/ent/db/billinginvoiceline/where.go
index fa998b8cca..80f267179a 100644
--- a/openmeter/ent/db/billinginvoiceline/where.go
+++ b/openmeter/ent/db/billinginvoiceline/where.go
@@ -100,7 +100,7 @@ func Description(v string) predicate.BillingInvoiceLine {
 }
 
 // Currency applies equality check predicate on the "currency" field. It's identical to CurrencyEQ.
-func Currency(v currencyx.Code) predicate.BillingInvoiceLine {
+func Currency(v currencyx.FiatCode) predicate.BillingInvoiceLine {
 	vc := string(v)
 	return predicate.BillingInvoiceLine(sql.FieldEQ(FieldCurrency, vc))
 }
@@ -586,19 +586,19 @@ func DescriptionContainsFold(v string) predicate.BillingInvoiceLine {
 }
 
 // CurrencyEQ applies the EQ predicate on the "currency" field.
-func CurrencyEQ(v currencyx.Code) predicate.BillingInvoiceLine {
+func CurrencyEQ(v currencyx.FiatCode) predicate.BillingInvoiceLine {
 	vc := string(v)
 	return predicate.BillingInvoiceLine(sql.FieldEQ(FieldCurrency, vc))
 }
 
 // CurrencyNEQ applies the NEQ predicate on the "currency" field.
-func CurrencyNEQ(v currencyx.Code) predicate.BillingInvoiceLine {
+func CurrencyNEQ(v currencyx.FiatCode) predicate.BillingInvoiceLine {
 	vc := string(v)
 	return predicate.BillingInvoiceLine(sql.FieldNEQ(FieldCurrency, vc))
 }
 
 // CurrencyIn applies the In predicate on the "currency" field.
-func CurrencyIn(vs ...currencyx.Code) predicate.BillingInvoiceLine {
+func CurrencyIn(vs ...currencyx.FiatCode) predicate.BillingInvoiceLine {
 	v := make([]any, len(vs))
 	for i := range v {
 		v[i] = string(vs[i])
@@ -607,7 +607,7 @@ func CurrencyIn(vs ...currencyx.Code) predicate.BillingInvoiceLine {
 }
 
 // CurrencyNotIn applies the NotIn predicate on the "currency" field.
-func CurrencyNotIn(vs ...currencyx.Code) predicate.BillingInvoiceLine {
+func CurrencyNotIn(vs ...currencyx.FiatCode) predicate.BillingInvoiceLine {
 	v := make([]any, len(vs))
 	for i := range v {
 		v[i] = string(vs[i])
@@ -616,55 +616,55 @@ func CurrencyNotIn(vs ...currencyx.Code) predicate.BillingInvoiceLine {
 }
 
 // CurrencyGT applies the GT predicate on the "currency" field.
-func CurrencyGT(v currencyx.Code) predicate.BillingInvoiceLine {
+func CurrencyGT(v currencyx.FiatCode) predicate.BillingInvoiceLine {
 	vc := string(v)
 	return predicate.BillingInvoiceLine(sql.FieldGT(FieldCurrency, vc))
 }
 
 // CurrencyGTE applies the GTE predicate on the "currency" field.
-func CurrencyGTE(v currencyx.Code) predicate.BillingInvoiceLine {
+func CurrencyGTE(v currencyx.FiatCode) predicate.BillingInvoiceLine {
 	vc := string(v)
 	return predicate.BillingInvoiceLine(sql.FieldGTE(FieldCurrency, vc))
 }
 
 // CurrencyLT applies the LT predicate on the "currency" field.
-func CurrencyLT(v currencyx.Code) predicate.BillingInvoiceLine {
+func CurrencyLT(v currencyx.FiatCode) predicate.BillingInvoiceLine {
 	vc := string(v)
 	return predicate.BillingInvoiceLine(sql.FieldLT(FieldCurrency, vc))
 }
 
 // CurrencyLTE applies the LTE predicate on the "currency" field.
-func CurrencyLTE(v currencyx.Code) predicate.BillingInvoiceLine {
+func CurrencyLTE(v currencyx.FiatCode) predicate.BillingInvoiceLine {
 	vc := string(v)
 	return predicate.BillingInvoiceLine(sql.FieldLTE(FieldCurrency, vc))
 }
 
 // CurrencyContains applies the Contains predicate on the "currency" field.
-func CurrencyContains(v currencyx.Code) predicate.BillingInvoiceLine {
+func CurrencyContains(v currencyx.FiatCode) predicate.BillingInvoiceLine {
 	vc := string(v)
 	return predicate.BillingInvoiceLine(sql.FieldContains(FieldCurrency, vc))
 }
 
 // CurrencyHasPrefix applies the HasPrefix predicate on the "currency" field.
-func CurrencyHasPrefix(v currencyx.Code) predicate.BillingInvoiceLine {
+func CurrencyHasPrefix(v currencyx.FiatCode) predicate.BillingInvoiceLine {
 	vc := string(v)
 	return predicate.BillingInvoiceLine(sql.FieldHasPrefix(FieldCurrency, vc))
 }
 
 // CurrencyHasSuffix applies the HasSuffix predicate on the "currency" field.
-func CurrencyHasSuffix(v currencyx.Code) predicate.BillingInvoiceLine {
+func CurrencyHasSuffix(v currencyx.FiatCode) predicate.BillingInvoiceLine {
 	vc := string(v)
 	return predicate.BillingInvoiceLine(sql.FieldHasSuffix(FieldCurrency, vc))
 }
 
 // CurrencyEqualFold applies the EqualFold predicate on the "currency" field.
-func CurrencyEqualFold(v currencyx.Code) predicate.BillingInvoiceLine {
+func CurrencyEqualFold(v currencyx.FiatCode) predicate.BillingInvoiceLine {
 	vc := string(v)
 	return predicate.BillingInvoiceLine(sql.FieldEqualFold(FieldCurrency, vc))
 }
 
 // CurrencyContainsFold applies the ContainsFold predicate on the "currency" field.
-func CurrencyContainsFold(v currencyx.Code) predicate.BillingInvoiceLine {
+func CurrencyContainsFold(v currencyx.FiatCode) predicate.BillingInvoiceLine {
 	vc := string(v)
 	return predicate.BillingInvoiceLine(sql.FieldContainsFold(FieldCurrency, vc))
 }
diff --git a/openmeter/ent/db/billinginvoiceline_create.go b/openmeter/ent/db/billinginvoiceline_create.go
index c61e088024..738311ded5 100644
--- a/openmeter/ent/db/billinginvoiceline_create.go
+++ b/openmeter/ent/db/billinginvoiceline_create.go
@@ -127,7 +127,7 @@ func (_c *BillingInvoiceLineCreate) SetNillableDescription(v *string) *BillingIn
 }
 
 // SetCurrency sets the "currency" field.
-func (_c *BillingInvoiceLineCreate) SetCurrency(v currencyx.Code) *BillingInvoiceLineCreate {
+func (_c *BillingInvoiceLineCreate) SetCurrency(v currencyx.FiatCode) *BillingInvoiceLineCreate {
 	_c.mutation.SetCurrency(v)
 	return _c
 }
diff --git a/openmeter/ent/db/billinginvoicesplitlinegroup.go b/openmeter/ent/db/billinginvoicesplitlinegroup.go
index 13c41fa499..b8e20f794e 100644
--- a/openmeter/ent/db/billinginvoicesplitlinegroup.go
+++ b/openmeter/ent/db/billinginvoicesplitlinegroup.go
@@ -40,7 +40,7 @@ type BillingInvoiceSplitLineGroup struct {
 	// Description holds the value of the "description" field.
 	Description *string `json:"description,omitempty"`
 	// Currency holds the value of the "currency" field.
-	Currency currencyx.Code `json:"currency,omitempty"`
+	Currency currencyx.FiatCode `json:"currency,omitempty"`
 	// ServicePeriodStart holds the value of the "service_period_start" field.
 	ServicePeriodStart time.Time `json:"service_period_start,omitempty"`
 	// ServicePeriodEnd holds the value of the "service_period_end" field.
@@ -238,7 +238,7 @@ func (_m *BillingInvoiceSplitLineGroup) assignValues(columns []string, values []
 			if value, ok := values[i].(*sql.NullString); !ok {
 				return fmt.Errorf("unexpected type %T for field currency", values[i])
 			} else if value.Valid {
-				_m.Currency = currencyx.Code(value.String)
+				_m.Currency = currencyx.FiatCode(value.String)
 			}
 		case billinginvoicesplitlinegroup.FieldServicePeriodStart:
 			if value, ok := values[i].(*sql.NullTime); !ok {
diff --git a/openmeter/ent/db/billinginvoicesplitlinegroup/where.go b/openmeter/ent/db/billinginvoicesplitlinegroup/where.go
index a02dc27b27..08ba26c2ac 100644
--- a/openmeter/ent/db/billinginvoicesplitlinegroup/where.go
+++ b/openmeter/ent/db/billinginvoicesplitlinegroup/where.go
@@ -97,7 +97,7 @@ func Description(v string) predicate.BillingInvoiceSplitLineGroup {
 }
 
 // Currency applies equality check predicate on the "currency" field. It's identical to CurrencyEQ.
-func Currency(v currencyx.Code) predicate.BillingInvoiceSplitLineGroup {
+func Currency(v currencyx.FiatCode) predicate.BillingInvoiceSplitLineGroup {
 	vc := string(v)
 	return predicate.BillingInvoiceSplitLineGroup(sql.FieldEQ(FieldCurrency, vc))
 }
@@ -498,19 +498,19 @@ func DescriptionContainsFold(v string) predicate.BillingInvoiceSplitLineGroup {
 }
 
 // CurrencyEQ applies the EQ predicate on the "currency" field.
-func CurrencyEQ(v currencyx.Code) predicate.BillingInvoiceSplitLineGroup {
+func CurrencyEQ(v currencyx.FiatCode) predicate.BillingInvoiceSplitLineGroup {
 	vc := string(v)
 	return predicate.BillingInvoiceSplitLineGroup(sql.FieldEQ(FieldCurrency, vc))
 }
 
 // CurrencyNEQ applies the NEQ predicate on the "currency" field.
-func CurrencyNEQ(v currencyx.Code) predicate.BillingInvoiceSplitLineGroup {
+func CurrencyNEQ(v currencyx.FiatCode) predicate.BillingInvoiceSplitLineGroup {
 	vc := string(v)
 	return predicate.BillingInvoiceSplitLineGroup(sql.FieldNEQ(FieldCurrency, vc))
 }
 
 // CurrencyIn applies the In predicate on the "currency" field.
-func CurrencyIn(vs ...currencyx.Code) predicate.BillingInvoiceSplitLineGroup {
+func CurrencyIn(vs ...currencyx.FiatCode) predicate.BillingInvoiceSplitLineGroup {
 	v := make([]any, len(vs))
 	for i := range v {
 		v[i] = string(vs[i])
@@ -519,7 +519,7 @@ func CurrencyIn(vs ...currencyx.Code) predicate.BillingInvoiceSplitLineGroup {
 }
 
 // CurrencyNotIn applies the NotIn predicate on the "currency" field.
-func CurrencyNotIn(vs ...currencyx.Code) predicate.BillingInvoiceSplitLineGroup {
+func CurrencyNotIn(vs ...currencyx.FiatCode) predicate.BillingInvoiceSplitLineGroup {
 	v := make([]any, len(vs))
 	for i := range v {
 		v[i] = string(vs[i])
@@ -528,55 +528,55 @@ func CurrencyNotIn(vs ...currencyx.Code) predicate.BillingInvoiceSplitLineGroup
 }
 
 // CurrencyGT applies the GT predicate on the "currency" field.
-func CurrencyGT(v currencyx.Code) predicate.BillingInvoiceSplitLineGroup {
+func CurrencyGT(v currencyx.FiatCode) predicate.BillingInvoiceSplitLineGroup {
 	vc := string(v)
 	return predicate.BillingInvoiceSplitLineGroup(sql.FieldGT(FieldCurrency, vc))
 }
 
 // CurrencyGTE applies the GTE predicate on the "currency" field.
-func CurrencyGTE(v currencyx.Code) predicate.BillingInvoiceSplitLineGroup {
+func CurrencyGTE(v currencyx.FiatCode) predicate.BillingInvoiceSplitLineGroup {
 	vc := string(v)
 	return predicate.BillingInvoiceSplitLineGroup(sql.FieldGTE(FieldCurrency, vc))
 }
 
 // CurrencyLT applies the LT predicate on the "currency" field.
-func CurrencyLT(v currencyx.Code) predicate.BillingInvoiceSplitLineGroup {
+func CurrencyLT(v currencyx.FiatCode) predicate.BillingInvoiceSplitLineGroup {
 	vc := string(v)
 	return predicate.BillingInvoiceSplitLineGroup(sql.FieldLT(FieldCurrency, vc))
 }
 
 // CurrencyLTE applies the LTE predicate on the "currency" field.
-func CurrencyLTE(v currencyx.Code) predicate.BillingInvoiceSplitLineGroup {
+func CurrencyLTE(v currencyx.FiatCode) predicate.BillingInvoiceSplitLineGroup {
 	vc := string(v)
 	return predicate.BillingInvoiceSplitLineGroup(sql.FieldLTE(FieldCurrency, vc))
 }
 
 // CurrencyContains applies the Contains predicate on the "currency" field.
-func CurrencyContains(v currencyx.Code) predicate.BillingInvoiceSplitLineGroup {
+func CurrencyContains(v currencyx.FiatCode) predicate.BillingInvoiceSplitLineGroup {
 	vc := string(v)
 	return predicate.BillingInvoiceSplitLineGroup(sql.FieldContains(FieldCurrency, vc))
 }
 
 // CurrencyHasPrefix applies the HasPrefix predicate on the "currency" field.
-func CurrencyHasPrefix(v currencyx.Code) predicate.BillingInvoiceSplitLineGroup {
+func CurrencyHasPrefix(v currencyx.FiatCode) predicate.BillingInvoiceSplitLineGroup {
 	vc := string(v)
 	return predicate.BillingInvoiceSplitLineGroup(sql.FieldHasPrefix(FieldCurrency, vc))
 }
 
 // CurrencyHasSuffix applies the HasSuffix predicate on the "currency" field.
-func CurrencyHasSuffix(v currencyx.Code) predicate.BillingInvoiceSplitLineGroup {
+func CurrencyHasSuffix(v currencyx.FiatCode) predicate.BillingInvoiceSplitLineGroup {
 	vc := string(v)
 	return predicate.BillingInvoiceSplitLineGroup(sql.FieldHasSuffix(FieldCurrency, vc))
 }
 
 // CurrencyEqualFold applies the EqualFold predicate on the "currency" field.
-func CurrencyEqualFold(v currencyx.Code) predicate.BillingInvoiceSplitLineGroup {
+func CurrencyEqualFold(v currencyx.FiatCode) predicate.BillingInvoiceSplitLineGroup {
 	vc := string(v)
 	return predicate.BillingInvoiceSplitLineGroup(sql.FieldEqualFold(FieldCurrency, vc))
 }
 
 // CurrencyContainsFold applies the ContainsFold predicate on the "currency" field.
-func CurrencyContainsFold(v currencyx.Code) predicate.BillingInvoiceSplitLineGroup {
+func CurrencyContainsFold(v currencyx.FiatCode) predicate.BillingInvoiceSplitLineGroup {
 	vc := string(v)
 	return predicate.BillingInvoiceSplitLineGroup(sql.FieldContainsFold(FieldCurrency, vc))
 }
diff --git a/openmeter/ent/db/billinginvoicesplitlinegroup_create.go b/openmeter/ent/db/billinginvoicesplitlinegroup_create.go
index 6a3bbdcbe3..c11435b51a 100644
--- a/openmeter/ent/db/billinginvoicesplitlinegroup_create.go
+++ b/openmeter/ent/db/billinginvoicesplitlinegroup_create.go
@@ -107,7 +107,7 @@ func (_c *BillingInvoiceSplitLineGroupCreate) SetNillableDescription(v *string)
 }
 
 // SetCurrency sets the "currency" field.
-func (_c *BillingInvoiceSplitLineGroupCreate) SetCurrency(v currencyx.Code) *BillingInvoiceSplitLineGroupCreate {
+func (_c *BillingInvoiceSplitLineGroupCreate) SetCurrency(v currencyx.FiatCode) *BillingInvoiceSplitLineGroupCreate {
 	_c.mutation.SetCurrency(v)
 	return _c
 }
diff --git a/openmeter/ent/db/entmixinaccessor.go b/openmeter/ent/db/entmixinaccessor.go
index 98635780eb..6bee7e2c0b 100644
--- a/openmeter/ent/db/entmixinaccessor.go
+++ b/openmeter/ent/db/entmixinaccessor.go
@@ -310,7 +310,7 @@ func (e *BillingGatheringInvoiceLine) GetDescription() *string {
 	return e.Description
 }
 
-func (e *BillingGatheringInvoiceLine) GetCurrency() currencyx.Code {
+func (e *BillingGatheringInvoiceLine) GetCurrency() currencyx.FiatCode {
 	return e.Currency
 }
 
@@ -546,7 +546,7 @@ func (e *BillingInvoiceLine) GetDescription() *string {
 	return e.Description
 }
 
-func (e *BillingInvoiceLine) GetCurrency() currencyx.Code {
+func (e *BillingInvoiceLine) GetCurrency() currencyx.FiatCode {
 	return e.Currency
 }
 
diff --git a/openmeter/ent/db/mutation.go b/openmeter/ent/db/mutation.go
index 71c1518831..96dc233295 100644
--- a/openmeter/ent/db/mutation.go
+++ b/openmeter/ent/db/mutation.go
@@ -11980,7 +11980,7 @@ type BillingGatheringInvoiceLineMutation struct {
 	deleted_at                       *time.Time
 	name                             *string
 	description                      *string
-	currency                         *currencyx.Code
+	currency                         *currencyx.FiatCode
 	service_period_start             *time.Time
 	service_period_end               *time.Time
 	tax_config                       *billing.TaxConfig
@@ -12461,12 +12461,12 @@ func (m *BillingGatheringInvoiceLineMutation) ResetDescription() {
 }
 
 // SetCurrency sets the "currency" field.
-func (m *BillingGatheringInvoiceLineMutation) SetCurrency(c currencyx.Code) {
-	m.currency = &c
+func (m *BillingGatheringInvoiceLineMutation) SetCurrency(cc currencyx.FiatCode) {
+	m.currency = &cc
 }
 
 // Currency returns the value of the "currency" field in the mutation.
-func (m *BillingGatheringInvoiceLineMutation) Currency() (r currencyx.Code, exists bool) {
+func (m *BillingGatheringInvoiceLineMutation) Currency() (r currencyx.FiatCode, exists bool) {
 	v := m.currency
 	if v == nil {
 		return
@@ -12477,7 +12477,7 @@ func (m *BillingGatheringInvoiceLineMutation) Currency() (r currencyx.Code, exis
 // OldCurrency returns the old "currency" field's value of the BillingGatheringInvoiceLine entity.
 // If the BillingGatheringInvoiceLine object wasn't provided to the builder, the object is fetched from the database.
 // An error is returned if the mutation operation is not UpdateOne, or the database query fails.
-func (m *BillingGatheringInvoiceLineMutation) OldCurrency(ctx context.Context) (v currencyx.Code, err error) {
+func (m *BillingGatheringInvoiceLineMutation) OldCurrency(ctx context.Context) (v currencyx.FiatCode, err error) {
 	if !m.op.Is(OpUpdateOne) {
 		return v, errors.New("OldCurrency is only allowed on UpdateOne operations")
 	}
@@ -14007,7 +14007,7 @@ func (m *BillingGatheringInvoiceLineMutation) SetField(name string, value ent.Va
 		m.SetDescription(v)
 		return nil
 	case billinggatheringinvoiceline.FieldCurrency:
-		v, ok := value.(currencyx.Code)
+		v, ok := value.(currencyx.FiatCode)
 		if !ok {
 			return fmt.Errorf("unexpected type %T for field %s", value, name)
 		}
@@ -14656,7 +14656,7 @@ type BillingInvoiceMutation struct {
 	draft_until                              *time.Time
 	quantity_snapshoted_at                   *time.Time
 	deletion_source                          *billing.ChangeSource
-	currency                                 *currencyx.Code
+	currency                                 *currencyx.FiatCode
 	due_at                                   *time.Time
 	status                                   *billing.StandardInvoiceStatus
 	status_details_cache                     *billing.StandardInvoiceStatusDetails
@@ -16840,12 +16840,12 @@ func (m *BillingInvoiceMutation) ResetDeletionSource() {
 }
 
 // SetCurrency sets the "currency" field.
-func (m *BillingInvoiceMutation) SetCurrency(c currencyx.Code) {
-	m.currency = &c
+func (m *BillingInvoiceMutation) SetCurrency(cc currencyx.FiatCode) {
+	m.currency = &cc
 }
 
 // Currency returns the value of the "currency" field in the mutation.
-func (m *BillingInvoiceMutation) Currency() (r currencyx.Code, exists bool) {
+func (m *BillingInvoiceMutation) Currency() (r currencyx.FiatCode, exists bool) {
 	v := m.currency
 	if v == nil {
 		return
@@ -16856,7 +16856,7 @@ func (m *BillingInvoiceMutation) Currency() (r currencyx.Code, exists bool) {
 // OldCurrency returns the old "currency" field's value of the BillingInvoice entity.
 // If the BillingInvoice object wasn't provided to the builder, the object is fetched from the database.
 // An error is returned if the mutation operation is not UpdateOne, or the database query fails.
-func (m *BillingInvoiceMutation) OldCurrency(ctx context.Context) (v currencyx.Code, err error) {
+func (m *BillingInvoiceMutation) OldCurrency(ctx context.Context) (v currencyx.FiatCode, err error) {
 	if !m.op.Is(OpUpdateOne) {
 		return v, errors.New("OldCurrency is only allowed on UpdateOne operations")
 	}
@@ -18714,7 +18714,7 @@ func (m *BillingInvoiceMutation) SetField(name string, value ent.Value) error {
 		m.SetDeletionSource(v)
 		return nil
 	case billinginvoice.FieldCurrency:
-		v, ok := value.(currencyx.Code)
+		v, ok := value.(currencyx.FiatCode)
 		if !ok {
 			return fmt.Errorf("unexpected type %T for field %s", value, name)
 		}
@@ -20205,7 +20205,7 @@ type BillingInvoiceLineMutation struct {
 	deleted_at                                     *time.Time
 	name                                           *string
 	description                                    *string
-	currency                                       *currencyx.Code
+	currency                                       *currencyx.FiatCode
 	tax_config                                     *billing.TaxConfig
 	tax_behavior                                   *productcatalog.TaxBehavior
 	amount                                         *alpacadecimal.Decimal
@@ -20725,12 +20725,12 @@ func (m *BillingInvoiceLineMutation) ResetDescription() {
 }
 
 // SetCurrency sets the "currency" field.
-func (m *BillingInvoiceLineMutation) SetCurrency(c currencyx.Code) {
-	m.currency = &c
+func (m *BillingInvoiceLineMutation) SetCurrency(cc currencyx.FiatCode) {
+	m.currency = &cc
 }
 
 // Currency returns the value of the "currency" field in the mutation.
-func (m *BillingInvoiceLineMutation) Currency() (r currencyx.Code, exists bool) {
+func (m *BillingInvoiceLineMutation) Currency() (r currencyx.FiatCode, exists bool) {
 	v := m.currency
 	if v == nil {
 		return
@@ -20741,7 +20741,7 @@ func (m *BillingInvoiceLineMutation) Currency() (r currencyx.Code, exists bool)
 // OldCurrency returns the old "currency" field's value of the BillingInvoiceLine entity.
 // If the BillingInvoiceLine object wasn't provided to the builder, the object is fetched from the database.
 // An error is returned if the mutation operation is not UpdateOne, or the database query fails.
-func (m *BillingInvoiceLineMutation) OldCurrency(ctx context.Context) (v currencyx.Code, err error) {
+func (m *BillingInvoiceLineMutation) OldCurrency(ctx context.Context) (v currencyx.FiatCode, err error) {
 	if !m.op.Is(OpUpdateOne) {
 		return v, errors.New("OldCurrency is only allowed on UpdateOne operations")
 	}
@@ -23314,7 +23314,7 @@ func (m *BillingInvoiceLineMutation) SetField(name string, value ent.Value) erro
 		m.SetDescription(v)
 		return nil
 	case billinginvoiceline.FieldCurrency:
-		v, ok := value.(currencyx.Code)
+		v, ok := value.(currencyx.FiatCode)
 		if !ok {
 			return fmt.Errorf("unexpected type %T for field %s", value, name)
 		}
@@ -26532,7 +26532,7 @@ type BillingInvoiceSplitLineGroupMutation struct {
 	deleted_at                             *time.Time
 	name                                   *string
 	description                            *string
-	currency                               *currencyx.Code
+	currency                               *currencyx.FiatCode
 	service_period_start                   *time.Time
 	service_period_end                     *time.Time
 	unique_reference_id                    *string
@@ -26957,12 +26957,12 @@ func (m *BillingInvoiceSplitLineGroupMutation) ResetDescription() {
 }
 
 // SetCurrency sets the "currency" field.
-func (m *BillingInvoiceSplitLineGroupMutation) SetCurrency(c currencyx.Code) {
-	m.currency = &c
+func (m *BillingInvoiceSplitLineGroupMutation) SetCurrency(cc currencyx.FiatCode) {
+	m.currency = &cc
 }
 
 // Currency returns the value of the "currency" field in the mutation.
-func (m *BillingInvoiceSplitLineGroupMutation) Currency() (r currencyx.Code, exists bool) {
+func (m *BillingInvoiceSplitLineGroupMutation) Currency() (r currencyx.FiatCode, exists bool) {
 	v := m.currency
 	if v == nil {
 		return
@@ -26973,7 +26973,7 @@ func (m *BillingInvoiceSplitLineGroupMutation) Currency() (r currencyx.Code, exi
 // OldCurrency returns the old "currency" field's value of the BillingInvoiceSplitLineGroup entity.
 // If the BillingInvoiceSplitLineGroup object wasn't provided to the builder, the object is fetched from the database.
 // An error is returned if the mutation operation is not UpdateOne, or the database query fails.
-func (m *BillingInvoiceSplitLineGroupMutation) OldCurrency(ctx context.Context) (v currencyx.Code, err error) {
+func (m *BillingInvoiceSplitLineGroupMutation) OldCurrency(ctx context.Context) (v currencyx.FiatCode, err error) {
 	if !m.op.Is(OpUpdateOne) {
 		return v, errors.New("OldCurrency is only allowed on UpdateOne operations")
 	}
@@ -28008,7 +28008,7 @@ func (m *BillingInvoiceSplitLineGroupMutation) SetField(name string, value ent.V
 		m.SetDescription(v)
 		return nil
 	case billinginvoicesplitlinegroup.FieldCurrency:
-		v, ok := value.(currencyx.Code)
+		v, ok := value.(currencyx.FiatCode)
 		if !ok {
 			return fmt.Errorf("unexpected type %T for field %s", value, name)
 		}
diff --git a/openmeter/ent/schema/billing.go b/openmeter/ent/schema/billing.go
index 6f4bb2d3c2..6a42e47c1d 100644
--- a/openmeter/ent/schema/billing.go
+++ b/openmeter/ent/schema/billing.go
@@ -290,7 +290,7 @@ type InvoiceLineBaseMixin struct {
 func (InvoiceLineBaseMixin) Fields() []ent.Field {
 	return []ent.Field{
 		field.String("currency").
-			GoType(currencyx.Code("")).
+			GoType(currencyx.FiatCode("")).
 			NotEmpty().
 			Immutable().
 			SchemaType(map[string]string{
@@ -326,7 +326,7 @@ func (StandardInvoiceLineIntentMixin) Annotations() []schema.Annotation {
 func (StandardInvoiceLineIntentMixin) Fields() []ent.Field {
 	return []ent.Field{
 		field.String("currency").
-			GoType(currencyx.Code("")).
+			GoType(currencyx.FiatCode("")).
 			NotEmpty().
 			Immutable().
 			SchemaType(map[string]string{
@@ -810,7 +810,7 @@ func (BillingInvoiceSplitLineGroup) Mixin() []ent.Mixin {
 func (BillingInvoiceSplitLineGroup) Fields() []ent.Field {
 	return []ent.Field{
 		field.String("currency").
-			GoType(currencyx.Code("")).
+			GoType(currencyx.FiatCode("")).
 			NotEmpty().
 			Immutable().
 			SchemaType(map[string]string{
@@ -1244,7 +1244,7 @@ func (BillingInvoice) Fields() []ent.Field {
 			Nillable(),
 
 		field.String("currency").
-			GoType(currencyx.Code("")).
+			GoType(currencyx.FiatCode("")).
 			NotEmpty().
 			Immutable().
 			SchemaType(map[string]string{
diff --git a/openmeter/notification/internal/rule.go b/openmeter/notification/internal/rule.go
index 83fa89f12d..3cc3530f34 100644
--- a/openmeter/notification/internal/rule.go
+++ b/openmeter/notification/internal/rule.go
@@ -202,7 +202,7 @@ func (t *TestEventGenerator) newTestInvoicePayload(ctx context.Context, namespac
 		},
 
 		Number:   lo.ToPtr("TEST-INV-1"),
-		Currency: currencyx.Code(currency.USD),
+		Currency: currencyx.FiatCode(currency.USD),
 		Lines: billing.NewStandardInvoiceLines([]*billing.StandardLine{
 			billing.NewFlatFeeLine(billing.NewFlatFeeLineInput{
 				Namespace: namespace,
diff --git a/test/app/custominvoicing/invocing_test.go b/test/app/custominvoicing/invocing_test.go
index 6eee125ec0..257ee5aea1 100644
--- a/test/app/custominvoicing/invocing_test.go
+++ b/test/app/custominvoicing/invocing_test.go
@@ -133,7 +133,7 @@ func (s *CustomInvoicingTestSuite) TestInvoicingFlowHooksEnabled() {
 		res, err := s.BillingService.CreatePendingInvoiceLines(ctx,
 			billing.CreatePendingInvoiceLinesInput{
 				Customer: customerEntity.GetID(),
-				Currency: currencyx.Code(currency.HUF),
+				Currency: currencyx.FiatCode(currency.HUF),
 				Lines: []billing.GatheringLine{
 					billing.NewFlatFeeGatheringLine(billing.NewFlatFeeLineInput{
 						Period: timeutil.ClosedPeriod{From: periodStart, To: periodEnd},
@@ -298,7 +298,7 @@ func (s *CustomInvoicingTestSuite) TestInvoicingFlowPaymentStatusOnly() {
 		res, err := s.BillingService.CreatePendingInvoiceLines(ctx,
 			billing.CreatePendingInvoiceLinesInput{
 				Customer: customerEntity.GetID(),
-				Currency: currencyx.Code(currency.HUF),
+				Currency: currencyx.FiatCode(currency.HUF),
 				Lines: []billing.GatheringLine{
 					billing.NewFlatFeeGatheringLine(billing.NewFlatFeeLineInput{
 						Period: timeutil.ClosedPeriod{From: periodStart, To: periodEnd},
diff --git a/test/app/stripe/invoice_credits_test.go b/test/app/stripe/invoice_credits_test.go
index c5c9d1eae0..f498874396 100644
--- a/test/app/stripe/invoice_credits_test.go
+++ b/test/app/stripe/invoice_credits_test.go
@@ -305,7 +305,7 @@ func (s *StripeInvoiceTestSuite) expectStripeInvoiceCreate(appID app.AppID, cust
 			InvoiceID:           invoiceID,
 			AutomaticTaxEnabled: true,
 			CollectionMethod:    billing.CollectionMethodChargeAutomatically,
-			Currency:            currencyx.Code("USD"),
+			Currency:            currencyx.FiatCode("USD"),
 			StripeCustomerID:    stripeCustomerID,
 		}).
 		Once().
diff --git a/test/app/stripe/invoice_test.go b/test/app/stripe/invoice_test.go
index 6e398d280c..96f5fd8679 100644
--- a/test/app/stripe/invoice_test.go
+++ b/test/app/stripe/invoice_test.go
@@ -393,7 +393,7 @@ func (s *StripeInvoiceTestSuite) TestComplexInvoice() {
 		pendingLines, err := s.BillingService.CreatePendingInvoiceLines(ctx,
 			billing.CreatePendingInvoiceLinesInput{
 				Customer: customerEntity.GetID(),
-				Currency: currencyx.Code(currency.USD),
+				Currency: currencyx.FiatCode(currency.USD),
 				Lines: []billing.GatheringLine{
 					{
 						// Covered case: Discount caused by maximum amount
@@ -1241,7 +1241,7 @@ func (s *StripeInvoiceTestSuite) TestEmptyInvoiceGenerationZeroUsage() {
 	pendingLines, err := s.BillingService.CreatePendingInvoiceLines(ctx,
 		billing.CreatePendingInvoiceLinesInput{
 			Customer: customerEntity.GetID(),
-			Currency: currencyx.Code(currency.USD),
+			Currency: currencyx.FiatCode(currency.USD),
 			Lines: []billing.GatheringLine{
 				{
 					GatheringLineBase: billing.GatheringLineBase{
@@ -1424,7 +1424,7 @@ func (s *StripeInvoiceTestSuite) TestSendInvoice() {
 	pendingLines, err := s.BillingService.CreatePendingInvoiceLines(ctx,
 		billing.CreatePendingInvoiceLinesInput{
 			Customer: customerEntity.GetID(),
-			Currency: currencyx.Code(currency.USD),
+			Currency: currencyx.FiatCode(currency.USD),
 			Lines: []billing.GatheringLine{
 				billing.NewFlatFeeGatheringLine(billing.NewFlatFeeLineInput{
 					Period:        timeutil.ClosedPeriod{From: periodStart, To: periodEnd},
diff --git a/test/billing/adapter_test.go b/test/billing/adapter_test.go
index 2babf8c5c0..56bbfd61f3 100644
--- a/test/billing/adapter_test.go
+++ b/test/billing/adapter_test.go
@@ -69,7 +69,7 @@ func (s *BillingAdapterTestSuite) setupInvoice(ctx context.Context, ns string) *
 		Customer:  *customerEntity,
 
 		Number:   "INV-123",
-		Currency: currencyx.Code(currency.USD),
+		Currency: currencyx.FiatCode(currency.USD),
 		Status:   billing.StandardInvoiceStatusGathering,
 
 		Profile:  *profile,
@@ -863,7 +863,7 @@ func (s *BillingAdapterTestSuite) TestHardDeleteGatheringInvoiceLines() {
 
 		res, err := s.BillingService.CreatePendingInvoiceLines(ctx, billing.CreatePendingInvoiceLinesInput{
 			Customer: customerEntity.GetID(),
-			Currency: currencyx.Code(currency.USD),
+			Currency: currencyx.FiatCode(currency.USD),
 			Lines: []billing.GatheringLine{
 				{
 					GatheringLineBase: billing.GatheringLineBase{
@@ -874,7 +874,7 @@ func (s *BillingAdapterTestSuite) TestHardDeleteGatheringInvoiceLines() {
 						ServicePeriod: timeutil.ClosedPeriod{From: periodStart, To: periodEnd},
 						InvoiceAt:     periodEnd,
 						ManagedBy:     billing.ManuallyManagedLine,
-						Currency:      currencyx.Code(currency.USD),
+						Currency:      currencyx.FiatCode(currency.USD),
 						RateCardDiscounts: billing.Discounts{
 							Percentage: &billing.PercentageDiscount{
 								PercentageDiscount: productcatalog.PercentageDiscount{
@@ -897,7 +897,7 @@ func (s *BillingAdapterTestSuite) TestHardDeleteGatheringInvoiceLines() {
 						ServicePeriod: timeutil.ClosedPeriod{From: periodStart, To: periodEnd},
 						InvoiceAt:     periodEnd,
 						ManagedBy:     billing.ManuallyManagedLine,
-						Currency:      currencyx.Code(currency.USD),
+						Currency:      currencyx.FiatCode(currency.USD),
 						RateCardDiscounts: billing.Discounts{
 							Percentage: &billing.PercentageDiscount{
 								PercentageDiscount: productcatalog.PercentageDiscount{
@@ -991,7 +991,7 @@ func (s *BillingAdapterTestSuite) TestHardDeleteGatheringInvoiceLinesNegative()
 
 		createdPendingLines, err := s.BillingService.CreatePendingInvoiceLines(ctx, billing.CreatePendingInvoiceLinesInput{
 			Customer: customerEntity.GetID(),
-			Currency: currencyx.Code(currency.USD),
+			Currency: currencyx.FiatCode(currency.USD),
 			Lines: []billing.GatheringLine{
 				{
 					GatheringLineBase: billing.GatheringLineBase{
@@ -1002,7 +1002,7 @@ func (s *BillingAdapterTestSuite) TestHardDeleteGatheringInvoiceLinesNegative()
 						ServicePeriod: timeutil.ClosedPeriod{From: line1PeriodStart, To: line1PeriodEnd},
 						InvoiceAt:     line1PeriodStart,
 						ManagedBy:     billing.ManuallyManagedLine,
-						Currency:      currencyx.Code(currency.USD),
+						Currency:      currencyx.FiatCode(currency.USD),
 						RateCardDiscounts: billing.Discounts{
 							Percentage: &billing.PercentageDiscount{
 								PercentageDiscount: productcatalog.PercentageDiscount{
@@ -1026,7 +1026,7 @@ func (s *BillingAdapterTestSuite) TestHardDeleteGatheringInvoiceLinesNegative()
 						ServicePeriod: timeutil.ClosedPeriod{From: line2PeriodStart, To: line2PeriodEnd},
 						InvoiceAt:     line2PeriodStart,
 						ManagedBy:     billing.ManuallyManagedLine,
-						Currency:      currencyx.Code(currency.USD),
+						Currency:      currencyx.FiatCode(currency.USD),
 						RateCardDiscounts: billing.Discounts{
 							Percentage: &billing.PercentageDiscount{
 								PercentageDiscount: productcatalog.PercentageDiscount{
diff --git a/test/billing/collection_test.go b/test/billing/collection_test.go
index 4e492c22da..0e7df670e0 100644
--- a/test/billing/collection_test.go
+++ b/test/billing/collection_test.go
@@ -99,7 +99,7 @@ func (s *CollectionTestSuite) TestUncollectableCollection() {
 
 	pendingLines, err := s.BillingService.CreatePendingInvoiceLines(ctx, billing.CreatePendingInvoiceLinesInput{
 		Customer: customer.GetID(),
-		Currency: currencyx.Code(currency.USD),
+		Currency: currencyx.FiatCode(currency.USD),
 		Lines: []billing.GatheringLine{
 			{
 				GatheringLineBase: billing.GatheringLineBase{
@@ -163,7 +163,7 @@ func (s *CollectionTestSuite) TestGatheringLineUnitConfigSnapshotRoundTrip() {
 
 	created, err := s.BillingService.CreatePendingInvoiceLines(ctx, billing.CreatePendingInvoiceLinesInput{
 		Customer: res.customer.GetID(),
-		Currency: currencyx.Code(currency.USD),
+		Currency: currencyx.FiatCode(currency.USD),
 		Lines: []billing.GatheringLine{
 			{
 				GatheringLineBase: billing.GatheringLineBase{
@@ -229,7 +229,7 @@ func (s *CollectionTestSuite) TestCollectionFlow() {
 	s.Run("validate collection_at calculation", func() {
 		res, err := s.BillingService.CreatePendingInvoiceLines(ctx, billing.CreatePendingInvoiceLinesInput{
 			Customer: customer.GetID(),
-			Currency: currencyx.Code(currency.USD),
+			Currency: currencyx.FiatCode(currency.USD),
 			Lines: []billing.GatheringLine{
 				{
 					GatheringLineBase: billing.GatheringLineBase{
@@ -428,7 +428,7 @@ func (s *CollectionTestSuite) TestCollectionFlowWithFlatFeeOnly() {
 			// Given
 			pendingLineResult, err := s.BillingService.CreatePendingInvoiceLines(ctx, billing.CreatePendingInvoiceLinesInput{
 				Customer: customer.GetID(),
-				Currency: currencyx.Code(currency.USD),
+				Currency: currencyx.FiatCode(currency.USD),
 				Lines:    []billing.GatheringLine{tc.line},
 			})
 			s.NoError(err)
@@ -482,7 +482,7 @@ func (s *CollectionTestSuite) TestCollectionFlowWithFlatFeeEditing() {
 
 	pendingLineResult, err := s.BillingService.CreatePendingInvoiceLines(ctx, billing.CreatePendingInvoiceLinesInput{
 		Customer: customer.GetID(),
-		Currency: currencyx.Code(currency.USD),
+		Currency: currencyx.FiatCode(currency.USD),
 		Lines: []billing.GatheringLine{
 			{
 				GatheringLineBase: billing.GatheringLineBase{
@@ -531,7 +531,7 @@ func (s *CollectionTestSuite) TestCollectionFlowWithFlatFeeEditing() {
 			invoice.Lines.Append(
 				billing.NewFlatFeeLine(billing.NewFlatFeeLineInput{
 					Namespace: namespace,
-					Currency:  currencyx.Code(currency.USD),
+					Currency:  currencyx.FiatCode(currency.USD),
 					InvoiceID: invoice.ID,
 					Period:    linePeriod,
 					InvoiceAt: linePeriod.To,
@@ -598,7 +598,7 @@ func (s *CollectionTestSuite) TestAnchoredAlignment_StandardInvoiceUsesLateEvent
 	periodEnd := now.Add(12 * time.Hour)
 	_, err = s.BillingService.CreatePendingInvoiceLines(ctx, billing.CreatePendingInvoiceLinesInput{
 		Customer: customerEntity.GetID(),
-		Currency: currencyx.Code(currency.USD),
+		Currency: currencyx.FiatCode(currency.USD),
 		Lines: []billing.GatheringLine{
 			{
 				GatheringLineBase: billing.GatheringLineBase{
@@ -697,7 +697,7 @@ func (s *CollectionTestSuite) TestAnchoredAlignment_AutomaticCollectionWaitsForA
 	periodEnd := now.Add(12 * time.Hour)
 	_, err = s.BillingService.CreatePendingInvoiceLines(ctx, billing.CreatePendingInvoiceLinesInput{
 		Customer: customerEntity.GetID(),
-		Currency: currencyx.Code(currency.USD),
+		Currency: currencyx.FiatCode(currency.USD),
 		Lines: []billing.GatheringLine{
 			{
 				GatheringLineBase: billing.GatheringLineBase{
@@ -760,7 +760,7 @@ func (s *CollectionTestSuite) TestAnchoredAlignment_StandardInvoiceWaitsForLateE
 	periodEnd := lo.Must(time.Parse(time.RFC3339, "2025-06-15T12:00:00Z"))
 	_, err = s.BillingService.CreatePendingInvoiceLines(ctx, billing.CreatePendingInvoiceLinesInput{
 		Customer: customerEntity.GetID(),
-		Currency: currencyx.Code(currency.USD),
+		Currency: currencyx.FiatCode(currency.USD),
 		Lines: []billing.GatheringLine{
 			{
 				GatheringLineBase: billing.GatheringLineBase{
@@ -800,7 +800,7 @@ func (s *CollectionTestSuite) TestAnchoredAlignment_StandardInvoiceWaitsForLateE
 
 	inv, err := s.BillingService.CreateStandardInvoiceFromGatheringLines(ctx, billing.CreateStandardInvoiceFromGatheringLinesInput{
 		Customer: customerEntity.GetID(),
-		Currency: currencyx.Code(currency.USD),
+		Currency: currencyx.FiatCode(currency.USD),
 		Lines:    invoices.Items[0].Lines.OrEmpty(),
 	})
 	s.NoError(err)
@@ -839,7 +839,7 @@ func (s *CollectionTestSuite) TestCollectionFlowWithUBPEditingExtendingCollectio
 
 	pendingLineResult, err := s.BillingService.CreatePendingInvoiceLines(ctx, billing.CreatePendingInvoiceLinesInput{
 		Customer: customer.GetID(),
-		Currency: currencyx.Code(currency.USD),
+		Currency: currencyx.FiatCode(currency.USD),
 		Lines: []billing.GatheringLine{
 			{
 				GatheringLineBase: billing.GatheringLineBase{
@@ -887,7 +887,7 @@ func (s *CollectionTestSuite) TestCollectionFlowWithUBPEditingExtendingCollectio
 							Namespace: namespace,
 							Name:      "UBP - unit - new",
 						}),
-						Currency:  currencyx.Code(currency.USD),
+						Currency:  currencyx.FiatCode(currency.USD),
 						InvoiceID: invoice.ID,
 						Period:    newLinePeriod,
 						InvoiceAt: newLinePeriod.To,
diff --git a/test/billing/discount_test.go b/test/billing/discount_test.go
index 6b4d7dff1d..cdf7a13f3d 100644
--- a/test/billing/discount_test.go
+++ b/test/billing/discount_test.go
@@ -91,7 +91,7 @@ func (s *DiscountsTestSuite) TestCorrelationIDHandling() {
 		res, err := s.BillingService.CreatePendingInvoiceLines(ctx,
 			billing.CreatePendingInvoiceLinesInput{
 				Customer: customerEntity.GetID(),
-				Currency: currencyx.Code(currency.USD),
+				Currency: currencyx.FiatCode(currency.USD),
 				Lines: []billing.GatheringLine{
 					{
 						GatheringLineBase: billing.GatheringLineBase{
@@ -105,7 +105,7 @@ func (s *DiscountsTestSuite) TestCorrelationIDHandling() {
 
 							ManagedBy: billing.ManuallyManagedLine,
 
-							Currency: currencyx.Code(currency.USD),
+							Currency: currencyx.FiatCode(currency.USD),
 							RateCardDiscounts: billing.Discounts{
 								Percentage: &billing.PercentageDiscount{
 									PercentageDiscount: productcatalog.PercentageDiscount{
@@ -221,7 +221,7 @@ func (s *DiscountsTestSuite) TestFlatPriceUsageDiscountIsNotPersisted() {
 	// - the pending line is created
 	_, err := s.BillingService.CreatePendingInvoiceLines(ctx, billing.CreatePendingInvoiceLinesInput{
 		Customer: customerEntity.GetID(),
-		Currency: currencyx.Code(currency.USD),
+		Currency: currencyx.FiatCode(currency.USD),
 		Lines: []billing.GatheringLine{
 			{
 				GatheringLineBase: billing.GatheringLineBase{
@@ -344,7 +344,7 @@ func (s *DiscountsTestSuite) TestUnitDiscountProgressiveBilling() {
 	res, err := s.BillingService.CreatePendingInvoiceLines(ctx,
 		billing.CreatePendingInvoiceLinesInput{
 			Customer: customerEntity.GetID(),
-			Currency: currencyx.Code(currency.USD),
+			Currency: currencyx.FiatCode(currency.USD),
 			Lines: []billing.GatheringLine{
 				{
 					GatheringLineBase: billing.GatheringLineBase{
@@ -358,7 +358,7 @@ func (s *DiscountsTestSuite) TestUnitDiscountProgressiveBilling() {
 
 						ManagedBy: billing.ManuallyManagedLine,
 
-						Currency: currencyx.Code(currency.USD),
+						Currency: currencyx.FiatCode(currency.USD),
 						RateCardDiscounts: billing.Discounts{
 							Usage: &billing.UsageDiscount{
 								UsageDiscount: productcatalog.UsageDiscount{
diff --git a/test/billing/invoice_test.go b/test/billing/invoice_test.go
index e0f23fe6ce..a417ed9f45 100644
--- a/test/billing/invoice_test.go
+++ b/test/billing/invoice_test.go
@@ -134,7 +134,7 @@ func (s *InvoicingTestSuite) TestPendingLineCreation() {
 		res, err := s.BillingService.CreatePendingInvoiceLines(ctx,
 			billing.CreatePendingInvoiceLinesInput{
 				Customer: customerEntity.GetID(),
-				Currency: currencyx.Code(currency.USD),
+				Currency: currencyx.FiatCode(currency.USD),
 				Lines: []billing.GatheringLine{
 					billing.NewFlatFeeGatheringLine(billing.NewFlatFeeLineInput{
 						Namespace: namespace,
@@ -168,7 +168,7 @@ func (s *InvoicingTestSuite) TestPendingLineCreation() {
 		res, err = s.BillingService.CreatePendingInvoiceLines(ctx,
 			billing.CreatePendingInvoiceLinesInput{
 				Customer: customerEntity.GetID(),
-				Currency: currencyx.Code(currency.HUF),
+				Currency: currencyx.FiatCode(currency.HUF),
 				Lines: []billing.GatheringLine{
 					billing.NewFlatFeeGatheringLine(billing.NewFlatFeeLineInput{
 						Period: timeutil.ClosedPeriod{From: periodStart, To: periodEnd},
@@ -226,7 +226,7 @@ func (s *InvoicingTestSuite) TestPendingLineCreation() {
 			Namespaces: []string{namespace},
 			Customers:  []string{customerEntity.ID},
 			Expand:     []billing.GatheringInvoiceExpand{billing.GatheringInvoiceExpandLines},
-			Currencies: []currencyx.Code{currencyx.Code(currency.USD)},
+			Currencies: []currencyx.FiatCode{currencyx.FiatCode(currency.USD)},
 		})
 		require.NoError(s.T(), err)
 		require.Len(s.T(), usdInvoices.Items, 1)
@@ -250,7 +250,7 @@ func (s *InvoicingTestSuite) TestPendingLineCreation() {
 				ManagedBy: billing.ManuallyManagedLine,
 				Engine:    billing.LineEngineTypeInvoice,
 
-				Currency: currencyx.Code(currency.USD),
+				Currency: currencyx.FiatCode(currency.USD),
 
 				Metadata: map[string]string{
 					"key": "value",
@@ -278,7 +278,7 @@ func (s *InvoicingTestSuite) TestPendingLineCreation() {
 				}),
 
 				Number:        "GATHER-TECU-USD-1",
-				Currency:      currencyx.Code(currency.USD),
+				Currency:      currencyx.FiatCode(currency.USD),
 				ServicePeriod: timeutil.ClosedPeriod{From: periodStart.Truncate(time.Second), To: periodEnd.Truncate(time.Second)},
 
 				// The customer snapshot
@@ -322,7 +322,7 @@ func (s *InvoicingTestSuite) TestPendingLineCreation() {
 			Namespaces: []string{namespace},
 			Customers:  []string{customerEntity.ID},
 			Expand:     billing.GatheringInvoiceExpandAll,
-			Currencies: []currencyx.Code{currencyx.Code(currency.HUF)},
+			Currencies: []currencyx.FiatCode{currencyx.FiatCode(currency.HUF)},
 		})
 		require.NoError(s.T(), err)
 		require.Len(s.T(), hufInvoices.Items, 1)
@@ -376,7 +376,7 @@ func (s *InvoicingTestSuite) TestPendingLineCreation() {
 		invoices, err := s.BillingService.ListGatheringInvoices(ctx, billing.ListGatheringInvoicesInput{
 			Namespaces: []string{namespace},
 			Customers:  []string{customerEntity.ID},
-			Currencies: []currencyx.Code{currencyx.Code(currency.USD)},
+			Currencies: []currencyx.FiatCode{currencyx.FiatCode(currency.USD)},
 		})
 		require.NoError(s.T(), err)
 		require.Len(s.T(), invoices.Items, 1)
@@ -423,7 +423,7 @@ func (s *InvoicingTestSuite) TestCreateInvoice() {
 	res, err := s.BillingService.CreatePendingInvoiceLines(ctx,
 		billing.CreatePendingInvoiceLinesInput{
 			Customer: customerEntity.GetID(),
-			Currency: currencyx.Code(currency.USD),
+			Currency: currencyx.FiatCode(currency.USD),
 			Lines: []billing.GatheringLine{
 				billing.NewFlatFeeGatheringLine(billing.NewFlatFeeLineInput{
 					Namespace: namespace,
@@ -603,7 +603,7 @@ func (s *InvoicingTestSuite) TestCreateInvoice() {
 		res, err := s.BillingService.CreatePendingInvoiceLines(ctx,
 			billing.CreatePendingInvoiceLinesInput{
 				Customer: customerEntity.GetID(),
-				Currency: currencyx.Code(currency.USD),
+				Currency: currencyx.FiatCode(currency.USD),
 				Lines: []billing.GatheringLine{
 					billing.NewFlatFeeGatheringLine(billing.NewFlatFeeLineInput{
 						Name:      "Test item1",
@@ -660,7 +660,7 @@ func (s *InvoicingTestSuite) TestListGatheringInvoices_CollectionAtFilterExclude
 	now := time.Now().UTC().Truncate(time.Second)
 	res, err := s.BillingService.CreatePendingInvoiceLines(ctx, billing.CreatePendingInvoiceLinesInput{
 		Customer: customerEntity.GetID(),
-		Currency: currencyx.Code(currency.USD),
+		Currency: currencyx.FiatCode(currency.USD),
 		Lines: []billing.GatheringLine{
 			billing.NewFlatFeeGatheringLine(
 				billing.NewFlatFeeLineInput{
@@ -1588,7 +1588,7 @@ func (s *InvoicingTestSuite) TestUBPProgressiveInvoicing() {
 		pendingLines, err := s.BillingService.CreatePendingInvoiceLines(ctx,
 			billing.CreatePendingInvoiceLinesInput{
 				Customer: customerEntity.GetID(),
-				Currency: currencyx.Code(currency.USD),
+				Currency: currencyx.FiatCode(currency.USD),
 				Lines: []billing.GatheringLine{
 					{
 						GatheringLineBase: billing.GatheringLineBase{
@@ -2459,7 +2459,7 @@ func (s *InvoicingTestSuite) TestUBPGraduatingFlatFeeTier1() {
 		pendingLines, err := s.BillingService.CreatePendingInvoiceLines(ctx,
 			billing.CreatePendingInvoiceLinesInput{
 				Customer: customerEntity.GetID(),
-				Currency: currencyx.Code(currency.USD),
+				Currency: currencyx.FiatCode(currency.USD),
 				Lines: []billing.GatheringLine{
 					{
 						GatheringLineBase: billing.GatheringLineBase{
@@ -2775,7 +2775,7 @@ func (s *InvoicingTestSuite) TestUBPNonProgressiveInvoicing() {
 		pendingLines, err := s.BillingService.CreatePendingInvoiceLines(ctx,
 			billing.CreatePendingInvoiceLinesInput{
 				Customer: customerEntity.GetID(),
-				Currency: currencyx.Code(currency.USD),
+				Currency: currencyx.FiatCode(currency.USD),
 				Lines: []billing.GatheringLine{
 					{
 						GatheringLineBase: billing.GatheringLineBase{
@@ -3275,7 +3275,7 @@ func (s *InvoicingTestSuite) TestGatheringInvoiceRecalculation() {
 		pendingLines, err := s.BillingService.CreatePendingInvoiceLines(ctx,
 			billing.CreatePendingInvoiceLinesInput{
 				Customer: customerEntity.GetID(),
-				Currency: currencyx.Code(currency.USD),
+				Currency: currencyx.FiatCode(currency.USD),
 				Lines: []billing.GatheringLine{
 					{
 						GatheringLineBase: billing.GatheringLineBase{
@@ -3442,7 +3442,7 @@ func (s *InvoicingTestSuite) TestEmptyInvoiceGenerationZeroUsage() {
 	pendingLines, err := s.BillingService.CreatePendingInvoiceLines(ctx,
 		billing.CreatePendingInvoiceLinesInput{
 			Customer: customerEntity.GetID(),
-			Currency: currencyx.Code(currency.USD),
+			Currency: currencyx.FiatCode(currency.USD),
 			Lines: []billing.GatheringLine{
 				{
 					GatheringLineBase: billing.GatheringLineBase{
@@ -3561,7 +3561,7 @@ func (s *InvoicingTestSuite) TestEmptyInvoiceGenerationZeroPrice() {
 	pendingLines, err := s.BillingService.CreatePendingInvoiceLines(ctx,
 		billing.CreatePendingInvoiceLinesInput{
 			Customer: customerEntity.GetID(),
-			Currency: currencyx.Code(currency.USD),
+			Currency: currencyx.FiatCode(currency.USD),
 			Lines: []billing.GatheringLine{
 				{
 					GatheringLineBase: billing.GatheringLineBase{
@@ -3743,7 +3743,7 @@ func (s *InvoicingTestSuite) TestProgressiveBillLate() {
 
 	pendingLines, err := s.BillingService.CreatePendingInvoiceLines(ctx, billing.CreatePendingInvoiceLinesInput{
 		Customer: customer.GetID(),
-		Currency: currencyx.Code(currency.USD),
+		Currency: currencyx.FiatCode(currency.USD),
 		Lines: []billing.GatheringLine{
 			{
 				GatheringLineBase: billing.GatheringLineBase{
@@ -3835,7 +3835,7 @@ func (s *InvoicingTestSuite) TestPartialInvoiceLinesOptions() {
 
 	pendingLines, err := s.BillingService.CreatePendingInvoiceLines(ctx, billing.CreatePendingInvoiceLinesInput{
 		Customer: customer.GetID(),
-		Currency: currencyx.Code(currency.USD),
+		Currency: currencyx.FiatCode(currency.USD),
 		Lines: []billing.GatheringLine{
 			{
 				GatheringLineBase: billing.GatheringLineBase{
@@ -3942,7 +3942,7 @@ func (s *InvoicingTestSuite) TestSortLines() {
 
 	pendingLines, err := s.BillingService.CreatePendingInvoiceLines(ctx, billing.CreatePendingInvoiceLinesInput{
 		Customer: customer.GetID(),
-		Currency: currencyx.Code(currency.USD),
+		Currency: currencyx.FiatCode(currency.USD),
 		Lines: []billing.GatheringLine{
 			{
 				GatheringLineBase: billing.GatheringLineBase{
@@ -4068,7 +4068,7 @@ func (s *InvoicingTestSuite) TestGatheringInvoicePeriodPersisting() {
 	// When
 	pendingLines, err := s.BillingService.CreatePendingInvoiceLines(ctx, billing.CreatePendingInvoiceLinesInput{
 		Customer: customer.GetID(),
-		Currency: currencyx.Code(currency.USD),
+		Currency: currencyx.FiatCode(currency.USD),
 		Lines: []billing.GatheringLine{
 			billing.NewFlatFeeGatheringLine(billing.NewFlatFeeLineInput{
 				Period:    timeutil.ClosedPeriod{From: periodStart, To: periodEnd},
@@ -4100,7 +4100,7 @@ func (s *InvoicingTestSuite) TestGatheringInvoicePeriodPersisting() {
 
 	pendingLines, err = s.BillingService.CreatePendingInvoiceLines(ctx, billing.CreatePendingInvoiceLinesInput{
 		Customer: customer.GetID(),
-		Currency: currencyx.Code(currency.USD),
+		Currency: currencyx.FiatCode(currency.USD),
 		Lines: []billing.GatheringLine{
 			billing.NewFlatFeeGatheringLine(billing.NewFlatFeeLineInput{
 				Period:    timeutil.ClosedPeriod{From: newPeriodStart, To: newPeriodEnd},
@@ -4167,7 +4167,7 @@ func (s *InvoicingTestSuite) TestDeleteGatheringInvoiceViaService() {
 	// - a gathering invoice with two active flat-fee lines
 	pendingLines, err := s.BillingService.CreatePendingInvoiceLines(ctx, billing.CreatePendingInvoiceLinesInput{
 		Customer: customer.GetID(),
-		Currency: currencyx.Code(currency.USD),
+		Currency: currencyx.FiatCode(currency.USD),
 		Lines: []billing.GatheringLine{
 			billing.NewFlatFeeGatheringLine(billing.NewFlatFeeLineInput{
 				Namespace: namespace,
@@ -4256,7 +4256,7 @@ func (s *InvoicingTestSuite) TestCreatePendingInvoiceLinesForDeletedCustomers()
 
 	pendingLines, err := s.BillingService.CreatePendingInvoiceLines(ctx, billing.CreatePendingInvoiceLinesInput{
 		Customer: customer.GetID(),
-		Currency: currencyx.Code(currency.USD),
+		Currency: currencyx.FiatCode(currency.USD),
 		Lines: []billing.GatheringLine{
 			billing.NewFlatFeeGatheringLine(billing.NewFlatFeeLineInput{
 				Period:    timeutil.ClosedPeriod{From: periodStart, To: periodEnd},
@@ -4292,7 +4292,7 @@ func (s *InvoicingTestSuite) TestCreatePendingInvoiceLinesForDeletedCustomers()
 
 	pendingLines, err = s.BillingService.CreatePendingInvoiceLines(ctx, billing.CreatePendingInvoiceLinesInput{
 		Customer: customer.GetID(),
-		Currency: currencyx.Code(currency.USD),
+		Currency: currencyx.FiatCode(currency.USD),
 		Lines: []billing.GatheringLine{
 			billing.NewFlatFeeGatheringLine(billing.NewFlatFeeLineInput{
 				Period:        timeutil.ClosedPeriod{From: clock.Now(), To: clock.Now().Add(time.Hour * 24)},
@@ -4397,7 +4397,7 @@ func (s *InvoicingTestSuite) TestSnapshotQuantityInvalidDatabaseState() {
 		pendingLines, err := s.BillingService.CreatePendingInvoiceLines(ctx,
 			billing.CreatePendingInvoiceLinesInput{
 				Customer: customerEntity.GetID(),
-				Currency: currencyx.Code(currency.USD),
+				Currency: currencyx.FiatCode(currency.USD),
 				Lines: []billing.GatheringLine{
 					{
 						GatheringLineBase: billing.GatheringLineBase{
@@ -4490,7 +4490,7 @@ func (s *InvoicingTestSuite) TestGatheringInvoiceEmulation() {
 	res, err := s.BillingService.CreatePendingInvoiceLines(ctx,
 		billing.CreatePendingInvoiceLinesInput{
 			Customer: customerEntity.GetID(),
-			Currency: currencyx.Code(currency.USD),
+			Currency: currencyx.FiatCode(currency.USD),
 			Lines: []billing.GatheringLine{
 				billing.NewFlatFeeGatheringLine(billing.NewFlatFeeLineInput{
 					Namespace:     namespace,
@@ -4575,7 +4575,7 @@ func (s *InvoicingTestSuite) TestUpdateInvoice() {
 		s.Run("given a gathering invoice with a line and a deleted line", func() {
 			res, err := s.BillingService.CreatePendingInvoiceLines(ctx, billing.CreatePendingInvoiceLinesInput{
 				Customer: customerEntity.GetID(),
-				Currency: currencyx.Code(currency.USD),
+				Currency: currencyx.FiatCode(currency.USD),
 				Lines:    testLines,
 			})
 			require.NoError(s.T(), err)
@@ -4670,7 +4670,7 @@ func (s *InvoicingTestSuite) TestUpdateInvoice() {
 		s.Run("given a draft invoice with a line and a deleted line", func() {
 			pendingLines, err := s.BillingService.CreatePendingInvoiceLines(ctx, billing.CreatePendingInvoiceLinesInput{
 				Customer: customerEntity.GetID(),
-				Currency: currencyx.Code(currency.USD),
+				Currency: currencyx.FiatCode(currency.USD),
 				Lines:    testLines,
 			})
 			require.NoError(s.T(), err)
diff --git a/test/billing/lineengine_test.go b/test/billing/lineengine_test.go
index 3648f591e0..c016133d2d 100644
--- a/test/billing/lineengine_test.go
+++ b/test/billing/lineengine_test.go
@@ -242,7 +242,7 @@ func (s *LineEngineTestSuite) createMeteredDraftInvoiceWaitingForCollectionForAp
 			Namespace: customerEntity.Namespace,
 			ID:        customerEntity.ID,
 		},
-		Currency: currencyx.Code(currency.USD),
+		Currency: currencyx.FiatCode(currency.USD),
 		Lines: []ombilling.GatheringLine{{
 			GatheringLineBase: ombilling.GatheringLineBase{
 				ManagedResource: models.ManagedResource{
@@ -397,7 +397,7 @@ func (s *LineEngineTestSuite) TestGatheringPreviewUsesPreviewLineEngineCallback(
 			Namespace: customerEntity.Namespace,
 			ID:        customerEntity.ID,
 		},
-		Currency: currencyx.Code(currency.USD),
+		Currency: currencyx.FiatCode(currency.USD),
 		Lines: []ombilling.GatheringLine{{
 			GatheringLineBase: ombilling.GatheringLineBase{
 				ManagedResource: models.ManagedResource{
diff --git a/test/billing/schemamigration_test.go b/test/billing/schemamigration_test.go
index 3b9e521fe7..313309d2b3 100644
--- a/test/billing/schemamigration_test.go
+++ b/test/billing/schemamigration_test.go
@@ -115,7 +115,7 @@ func (s *SchemaMigrationTestSuite) TestSchemaLevel1Migration() {
 
 		_, err := s.BillingService.CreatePendingInvoiceLines(ctx, billing.CreatePendingInvoiceLinesInput{
 			Customer: customerEntity.GetID(),
-			Currency: currencyx.Code(currency.USD),
+			Currency: currencyx.FiatCode(currency.USD),
 			Lines: []billing.GatheringLine{
 				{
 					GatheringLineBase: billing.GatheringLineBase{
@@ -126,7 +126,7 @@ func (s *SchemaMigrationTestSuite) TestSchemaLevel1Migration() {
 						ServicePeriod: timeutil.ClosedPeriod{From: periodStart, To: periodEnd},
 						InvoiceAt:     periodEnd,
 						ManagedBy:     billing.ManuallyManagedLine,
-						Currency:      currencyx.Code(currency.USD),
+						Currency:      currencyx.FiatCode(currency.USD),
 						RateCardDiscounts: billing.Discounts{
 							Percentage: &billing.PercentageDiscount{
 								PercentageDiscount: productcatalog.PercentageDiscount{
@@ -149,7 +149,7 @@ func (s *SchemaMigrationTestSuite) TestSchemaLevel1Migration() {
 						ServicePeriod: timeutil.ClosedPeriod{From: periodStart, To: periodEnd},
 						InvoiceAt:     periodEnd,
 						ManagedBy:     billing.ManuallyManagedLine,
-						Currency:      currencyx.Code(currency.USD),
+						Currency:      currencyx.FiatCode(currency.USD),
 						RateCardDiscounts: billing.Discounts{
 							Percentage: &billing.PercentageDiscount{
 								PercentageDiscount: productcatalog.PercentageDiscount{
@@ -217,7 +217,7 @@ func (s *SchemaMigrationTestSuite) TestSchemaLevel1Migration() {
 
 		result, err := s.BillingService.CreatePendingInvoiceLines(ctx, billing.CreatePendingInvoiceLinesInput{
 			Customer: customerEntity.GetID(),
-			Currency: currencyx.Code(currency.USD),
+			Currency: currencyx.FiatCode(currency.USD),
 			Lines: []billing.GatheringLine{
 				{
 					GatheringLineBase: billing.GatheringLineBase{
@@ -228,7 +228,7 @@ func (s *SchemaMigrationTestSuite) TestSchemaLevel1Migration() {
 						ServicePeriod: timeutil.ClosedPeriod{From: periodStart, To: periodEnd},
 						InvoiceAt:     periodEnd,
 						ManagedBy:     billing.ManuallyManagedLine,
-						Currency:      currencyx.Code(currency.USD),
+						Currency:      currencyx.FiatCode(currency.USD),
 						FeatureKey:    featureFlatPerUnit.Key,
 						Price: lo.FromPtr(productcatalog.NewPriceFrom(productcatalog.FlatPrice{
 							Amount: alpacadecimal.NewFromFloat(100),
diff --git a/test/billing/suite.go b/test/billing/suite.go
index 60cdf2aff1..2522f64f9f 100644
--- a/test/billing/suite.go
+++ b/test/billing/suite.go
@@ -466,7 +466,7 @@ func (s *BaseSuite) CreateGatheringInvoice(t *testing.T, ctx context.Context, in
 	res, err := s.BillingService.CreatePendingInvoiceLines(ctx,
 		billing.CreatePendingInvoiceLinesInput{
 			Customer: in.Customer.GetID(),
-			Currency: currencyx.Code(currency.USD),
+			Currency: currencyx.FiatCode(currency.USD),
 			Lines: []billing.GatheringLine{
 				billing.NewFlatFeeGatheringLine(
 					billing.NewFlatFeeLineInput{
@@ -476,7 +476,7 @@ func (s *BaseSuite) CreateGatheringInvoice(t *testing.T, ctx context.Context, in
 						ManagedBy:     billing.ManuallyManagedLine,
 						Name:          "Test item1",
 						PerUnitAmount: alpacadecimal.NewFromFloat(100),
-						Currency:      currencyx.Code(currency.USD),
+						Currency:      currencyx.FiatCode(currency.USD),
 						Metadata: map[string]string{
 							"key": "value",
 						},
@@ -491,7 +491,7 @@ func (s *BaseSuite) CreateGatheringInvoice(t *testing.T, ctx context.Context, in
 						ManagedBy:     billing.ManuallyManagedLine,
 						Name:          "Test item2",
 						PerUnitAmount: alpacadecimal.NewFromFloat(200),
-						Currency:      currencyx.Code(currency.USD),
+						Currency:      currencyx.FiatCode(currency.USD),
 						Metadata: map[string]string{
 							"key": "value",
 						},
diff --git a/test/billing/tax_test.go b/test/billing/tax_test.go
index 24e15dbe6e..5709b42bff 100644
--- a/test/billing/tax_test.go
+++ b/test/billing/tax_test.go
@@ -209,7 +209,7 @@ func (s *InvoicingTaxTestSuite) TestLineSplittingRetainsTaxConfig() {
 	res, err := s.BillingService.CreatePendingInvoiceLines(ctx,
 		billing.CreatePendingInvoiceLinesInput{
 			Customer: customer.GetID(),
-			Currency: currencyx.Code(currency.USD),
+			Currency: currencyx.FiatCode(currency.USD),
 			Lines: []billing.GatheringLine{
 				{
 					GatheringLineBase: billing.GatheringLineBase{
@@ -296,7 +296,7 @@ func (s *InvoicingTaxTestSuite) generateDraftInvoice(ctx context.Context, custom
 	res, err := s.BillingService.CreatePendingInvoiceLines(ctx,
 		billing.CreatePendingInvoiceLinesInput{
 			Customer: customer.GetID(),
-			Currency: currencyx.Code(currency.USD),
+			Currency: currencyx.FiatCode(currency.USD),
 			Lines: []billing.GatheringLine{
 				billing.NewFlatFeeGatheringLine(billing.NewFlatFeeLineInput{
 					Period: timeutil.ClosedPeriod{From: now, To: now.Add(time.Hour * 24)},
diff --git a/test/billing/taxcode_dual_write_test.go b/test/billing/taxcode_dual_write_test.go
index 9731fc2189..6a118eb6b7 100644
--- a/test/billing/taxcode_dual_write_test.go
+++ b/test/billing/taxcode_dual_write_test.go
@@ -524,7 +524,7 @@ func (s *TaxCodeDualWriteTestSuite) TestSnapshotTaxCodeIntoLinesOnAdvance() {
 
 	_, err := s.BillingService.CreatePendingInvoiceLines(ctx, billing.CreatePendingInvoiceLinesInput{
 		Customer: cust.GetID(),
-		Currency: currencyx.Code(currency.USD),
+		Currency: currencyx.FiatCode(currency.USD),
 		Lines: []billing.GatheringLine{
 			billing.NewFlatFeeGatheringLine(billing.NewFlatFeeLineInput{
 				Namespace:     ns,
@@ -570,7 +570,7 @@ func (s *TaxCodeDualWriteTestSuite) TestSnapshotLineOwnCodeTakesPrecedence() {
 
 	_, err := s.BillingService.CreatePendingInvoiceLines(ctx, billing.CreatePendingInvoiceLinesInput{
 		Customer: cust.GetID(),
-		Currency: currencyx.Code(currency.USD),
+		Currency: currencyx.FiatCode(currency.USD),
 		Lines: []billing.GatheringLine{
 			{
 				GatheringLineBase: billing.GatheringLineBase{
@@ -628,7 +628,7 @@ func (s *TaxCodeDualWriteTestSuite) TestSnapshotPreservesExistingTaxCodeID() {
 	// Create a pending line with the TaxCodeID already stamped (as subscription sync would do).
 	_, err := s.BillingService.CreatePendingInvoiceLines(ctx, billing.CreatePendingInvoiceLinesInput{
 		Customer: cust.GetID(),
-		Currency: currencyx.Code(currency.USD),
+		Currency: currencyx.FiatCode(currency.USD),
 		Lines: []billing.GatheringLine{
 			{
 				GatheringLineBase: billing.GatheringLineBase{
@@ -696,7 +696,7 @@ func (s *TaxCodeDualWriteTestSuite) TestSimulateInvoiceReadOnly() {
 	result, err := s.BillingService.SimulateInvoice(ctx, billing.SimulateInvoiceInput{
 		Namespace:  ns,
 		CustomerID: &cust.ID,
-		Currency:   currencyx.Code(currency.USD),
+		Currency:   currencyx.FiatCode(currency.USD),
 		Lines:      billing.NewStandardInvoiceLines([]*billing.StandardLine{line}),
 	})
 	s.NoError(err)
diff --git a/test/billing/unitconfig_legacy_test.go b/test/billing/unitconfig_legacy_test.go
index e7d5539b89..528e6e03c3 100644
--- a/test/billing/unitconfig_legacy_test.go
+++ b/test/billing/unitconfig_legacy_test.go
@@ -67,7 +67,7 @@ func (s *legacyUnitConfigRatingSuite) TestRatesConvertedQuantity() {
 
 	_, err := s.BillingService.CreatePendingInvoiceLines(ctx, billing.CreatePendingInvoiceLinesInput{
 		Customer: cust.GetID(),
-		Currency: currencyx.Code(currency.USD),
+		Currency: currencyx.FiatCode(currency.USD),
 		Lines: []billing.GatheringLine{
 			{
 				GatheringLineBase: billing.GatheringLineBase{
diff --git a/test/credits/credit_then_invoice_test.go b/test/credits/credit_then_invoice_test.go
index d469b74bea..7a0f141413 100644
--- a/test/credits/credit_then_invoice_test.go
+++ b/test/credits/credit_then_invoice_test.go
@@ -5314,7 +5314,7 @@ func (s *CreditThenInvoiceTestSuite) mustGatheringLinesForCharge(namespace, cust
 	gatheringInvoices, err := s.BillingService.ListGatheringInvoices(s.T().Context(), billing.ListGatheringInvoicesInput{
 		Namespaces:     []string{namespace},
 		Customers:      []string{customerID},
-		Currencies:     []currencyx.Code{USD},
+		Currencies:     []currencyx.FiatCode{currencyx.FiatCode(USD)},
 		IncludeDeleted: includeDeletedLines,
 		Expand:         expand,
 	})
diff --git a/test/credits/sanity_test.go b/test/credits/sanity_test.go
index 6811658974..b36aedaf9f 100644
--- a/test/credits/sanity_test.go
+++ b/test/credits/sanity_test.go
@@ -3298,7 +3298,7 @@ func (s *SanitySuite) TestFlatFeeCreditOnlySanity() {
 		gatheringInvoices, err := s.BillingService.ListGatheringInvoices(ctx, billing.ListGatheringInvoicesInput{
 			Namespaces: []string{ns},
 			Customers:  []string{cust.ID},
-			Currencies: []currencyx.Code{USD},
+			Currencies: []currencyx.FiatCode{currencyx.FiatCode(USD)},
 			Expand:     []billing.GatheringInvoiceExpand{billing.GatheringInvoiceExpandLines},
 		})
 		s.NoError(err)
@@ -3341,7 +3341,7 @@ func (s *SanitySuite) TestFlatFeeCreditOnlySanity() {
 		gatheringInvoices, err := s.BillingService.ListGatheringInvoices(ctx, billing.ListGatheringInvoicesInput{
 			Namespaces: []string{ns},
 			Customers:  []string{cust.ID},
-			Currencies: []currencyx.Code{USD},
+			Currencies: []currencyx.FiatCode{currencyx.FiatCode(USD)},
 			Expand:     []billing.GatheringInvoiceExpand{billing.GatheringInvoiceExpandLines},
 		})
 		s.NoError(err)
diff --git a/test/customer/subject.go b/test/customer/subject.go
index b0ffdf673f..11713b0c65 100644
--- a/test/customer/subject.go
+++ b/test/customer/subject.go
@@ -393,7 +393,7 @@ func (s *CustomerHandlerTestSuite) TestMultiSubjectIntegrationFlow(ctx context.C
 			Namespace: s.namespace,
 			ID:        createdCustomer.ID,
 		},
-		Currency: currencyx.Code("USD"),
+		Currency: currencyx.FiatCode("USD"),
 		Lines:    []billing.GatheringLine{pendingLine},
 	})
 	require.NoError(t, err, "creating pending invoice lines should succeed")