Fix stock capital period handling (#1675)

Author: MaxGhenis

policyengine_uk/tests/test_stock_capital_periods.py

@@ -0,0 +1,49 @@
+from policyengine_uk import Simulation
+
+
+def test_uc_capital_stocks_are_not_prorated_in_monthly_calculations():
+    situation = {
+        "people": {"person": {"age": {"2026": 30}}},
+        "benunits": {
+            "benunit": {
+                "members": ["person"],
+                "would_claim_uc": {"2026": True},
+            }
+        },
+        "households": {
+            "household": {
+                "members": ["person"],
+                "savings": {"2026": 12_000},
+                "other_residential_property_value": {"2026": 12_000},
+                "corporate_wealth": {"2026": 12_000},
+            }
+        },
+    }
+    simulation = Simulation(situation=situation)
+
+    assert simulation.calculate("savings", "2026-01")[0] == 12_000
+    assert simulation.calculate("corporate_wealth", "2026-01")[0] == 12_000
+    assert simulation.calculate("uc_assessable_capital", "2026-01")[0] == 36_000
+    assert not simulation.calculate("is_uc_eligible", "2026-01")[0]
+
+
+def test_pension_credit_capital_stocks_are_not_prorated_monthly():
+    situation = {
+        "people": {"person": {"age": {"2026": 70}}},
+        "benunits": {"benunit": {"members": ["person"]}},
+        "households": {
+            "household": {
+                "members": ["person"],
+                "savings": {"2026": 12_000},
+                "owned_land": {"2026": 12_000},
+                "corporate_wealth": {"2026": 12_000},
+            }
+        },
+    }
+    simulation = Simulation(situation=situation)
+
+    assert simulation.calculate("savings", "2026-01")[0] == 12_000
+    assert (
+        simulation.calculate("pension_credit_assessable_capital", "2026-01")[0]
+        == 36_000
+    )

policyengine_uk/variables/gov/dwp/esa_income_assessable_capital.py

@@ -15,6 +15,7 @@ class esa_income_assessable_capital(Variable):
     )
     definition_period = YEAR
     unit = GBP
+    quantity_type = STOCK
 
     def formula(benunit, period, parameters):
         ESA = parameters(period).gov.dwp.ESA.income

policyengine_uk/variables/gov/dwp/housing_benefit/housing_benefit_assessable_capital.py

@@ -11,13 +11,14 @@ class housing_benefit_assessable_capital(Variable):
     )
     definition_period = YEAR
     unit = GBP
+    quantity_type = STOCK
 
     def formula(benunit, period, parameters):
         household = benunit.household
         person = benunit.members
         any_over_SP_age = benunit.any(person("is_SP_age", period))
         p = parameters(period).gov.dwp.housing_benefit.means_test.capital
-        household_capital = add(household, period, p.sources)
+        household_capital = sum(household(source, period) for source in p.sources)
         benunit_adults = add(benunit, period, ["is_adult"])
         household_adults = benunit.max(
             person.household.sum(person.household.members("is_adult", period))

policyengine_uk/variables/gov/dwp/income_support_assessable_capital.py

@@ -14,6 +14,7 @@ class income_support_assessable_capital(Variable):
     )
     definition_period = YEAR
     unit = GBP
+    quantity_type = STOCK
 
     def formula(benunit, period, parameters):
         IS = parameters(period).gov.dwp.income_support

policyengine_uk/variables/gov/dwp/jsa_income_assessable_capital.py

@@ -15,6 +15,7 @@ class jsa_income_assessable_capital(Variable):
     )
     definition_period = YEAR
     unit = GBP
+    quantity_type = STOCK
 
     def formula(benunit, period, parameters):
         JSA = parameters(period).gov.dwp.JSA.income

policyengine_uk/variables/gov/dwp/pension_credit/pension_credit_assessable_capital.py

@@ -13,12 +13,13 @@ class pension_credit_assessable_capital(Variable):
     )
     definition_period = YEAR
     unit = GBP
+    quantity_type = STOCK
 
     def formula(benunit, period, parameters):
         household = benunit.household
         person = benunit.members
         p = parameters(period).gov.dwp.pension_credit.income.capital
-        household_capital = add(household, period, p.sources)
+        household_capital = sum(household(source, period) for source in p.sources)
         any_pension_age = benunit.any(person("is_SP_age", period))
         benunit_pension_age_adults = benunit.sum(person("is_SP_age", period))
         household_pension_age_adults = benunit.max(

policyengine_uk/variables/gov/dwp/universal_credit/household_uc_reported_capital.py

@@ -7,6 +7,7 @@ class household_uc_reported_capital(Variable):
     label = "Household Universal Credit capital explicitly reported by benunits"
     definition_period = YEAR
     unit = GBP
+    quantity_type = STOCK
 
     def formula(household, period, parameters):
         person = household.members

policyengine_uk/variables/gov/dwp/universal_credit/uc_assessable_capital.py

@@ -11,11 +11,14 @@ class uc_assessable_capital(Variable):
     )
     definition_period = YEAR
     unit = GBP
+    quantity_type = STOCK
 
     def formula(benunit, period, parameters):
         household = benunit.household
         p = parameters(period).gov.dwp.universal_credit.means_test
-        household_capital = add(household, period, p.capital.sources)
+        household_capital = sum(
+            household(source, period) for source in p.capital.sources
+        )
         benunit_adults = add(benunit, period, ["is_adult"])
         household_reported_capital = household("household_uc_reported_capital", period)
         household_unreported_adults = household(

policyengine_uk/variables/gov/dwp/universal_credit/uc_reported_capital.py

@@ -12,4 +12,5 @@ class uc_reported_capital(Variable):
     )
     definition_period = YEAR
     unit = GBP
+    quantity_type = STOCK
     default_value = -1

policyengine_uk/variables/gov/hmrc/student_loans/student_loan_balance.py

@@ -11,4 +11,5 @@ class student_loan_balance(Variable):
     )
     definition_period = YEAR
     unit = GBP
+    quantity_type = STOCK
     default_value = 0