Zero Maine's 2025 affordability payment in siitax comparisons (#1056)

changelog.d/me-affordability-payment.fixed.md

@@ -0,0 +1 @@
+Zero Maine's 2025 affordability payment (HP 1491 Part T direct payment, modeled in PolicyEngine as a refundable credit) so it stays out of siitax for ME comparisons.

policyengine_taxsim/runners/policyengine_runner.py

@@ -191,6 +191,7 @@ def _initialize_dataset_structure(self) -> dict:
             "early_head_start",  # Early Head Start should be 0 to match TAXSIM (which doesn't model Early Head Start)
             "commodity_supplemental_food_program",  # Commodity supplemental food program should be 0 to match TAXSIM (which doesn't model this program)
             "medical_expense_health_insurance_premiums",  # TAXSIM has no medical-expense input; zero PE's imputed Medicare Part B premiums so they don't flow into state medical exemptions/deductions via the federal itemized medical deduction
+            "me_affordability_payment",  # Maine's 2025 affordability payment (HP 1491 Part T) is a direct payment mailed by the assessor in 2026-27, not a 1040ME line; PE models it as a refundable credit, which would land in siitax
         }
 
         # Combine all variables
@@ -904,6 +905,9 @@ def generate(self) -> None:
             data["ok_use_tax"][year_int] = np.zeros(
                 n_year_records
             )  # Prevent Oklahoma use tax calculations
+            data["me_affordability_payment"][year_int] = np.zeros(
+                n_year_records
+            )  # Maine's 2025 affordability payment (HP 1491 Part T, $300/adult) is a direct payment mailed in 2026-27 based on the 2025 return, not a 1040ME line item; TAXSIM/TaxAct never report it, so keep it out of siitax
 
             # Set person-level variables that need to be set per person, not per tax unit
             total_people_for_year = len(person_data.get("person_id", []))

tests/test_me_affordability_payment.py

@@ -0,0 +1,48 @@
+"""
+Maine's 2025 affordability payment must stay out of siitax.
+
+H.P. 1491 (132nd Leg.), Part T creates a one-time $300-per-adult payment
+for TY2025 filers under FAGI limits, paid by the State Tax Assessor from a
+Special Revenue Fund in 2026-27. It is not a 1040ME line item, so neither
+TAXSIM nor commercial software reports it in state liability. PolicyEngine
+models it as a refundable credit (me_affordability_payment) to surface it
+in tax-unit outputs; the emulator zeroes it so ME 2025 comparisons are not
+off by $300-600 per record. See taxsim #1056.
+"""
+
+import io
+
+import pandas as pd
+from click.testing import CliRunner
+
+from policyengine_taxsim.cli import cli
+
+ME = 20
+
+
+def _row(year: int, mstat: int, page: int, sage: int, pwages: float):
+    record = (
+        f"taxsimid,year,state,mstat,page,sage,depx,pwages,idtl\n"
+        f"1,{year},{ME},{mstat},{page},{sage},0,{pwages},2\n"
+    )
+    result = CliRunner().invoke(cli, [], input=record)
+    assert result.exit_code == 0, f"CLI failed: {result.output}\n{result.exception}"
+    out = result.output
+    idx = out.find("taxsimid,")
+    assert idx != -1, f"No CSV output:\n{out}"
+    return pd.read_csv(io.StringIO(out[idx:])).iloc[0]
+
+
+def test_me_2025_joint_excludes_affordability_payment():
+    """A 2025 ME joint filer under the FAGI limit must not receive the
+    $600 ($300 x 2 adults) affordability payment through siitax.
+
+    From taxsim #1056: MFJ ages 23/24, ~$10.5K wages. With the payment
+    included, siitax carried an extra -$600; the couple's only remaining
+    refundable credits (PTFC/STFC) total well under $600, so siitax must
+    stay above (less negative than) -600."""
+    r = _row(year=2025, mstat=2, page=23, sage=24, pwages=10476.19)
+    assert r["siitax"] > -600, (
+        f"siitax {r['siitax']} suggests the $600 affordability payment "
+        f"is still included in ME state liability"
+    )