Add SC H.4216 budget impact test

policyengine_us_data/tests/test_calibration/test_sc_h4216_budget_impact.py

@@ -0,0 +1,43 @@
+from policyengine_core.reforms import Reform
+from policyengine_us import Microsimulation
+from policyengine_us.reforms.states.sc.h4216.sc_h4216 import (
+    create_sc_h4216,
+)
+
+SC_DATASET = "hf://policyengine/policyengine-us-data/staging/states/SC.h5"
+
+PARAM_OVERRIDES = {
+    "gov.contrib.states.sc.h4216.in_effect": {
+        "2026-01-01.2100-12-31": True,
+    },
+    "gov.contrib.states.sc.h4216.rates[1].rate": {
+        "2026-01-01.2100-12-31": 0.0539,
+    },
+}
+
+
+def test_sc_h4216_budget_impact():
+    structural_reform = create_sc_h4216()
+    param_reform = Reform.from_dict(PARAM_OVERRIDES, country_id="us")
+    full_reform = (structural_reform, param_reform)
+
+    baseline = Microsimulation(dataset=SC_DATASET)
+    reformed = Microsimulation(reform=full_reform, dataset=SC_DATASET)
+
+    baseline_tax = baseline.calculate("sc_income_tax", 2026, map_to="tax_unit")
+    reform_tax = reformed.calculate("sc_income_tax", 2026, map_to="tax_unit")
+    weight = baseline.calculate("tax_unit_weight", 2026)
+
+    # BUG (double-weighting): MicroSeries.sum() already multiplies
+    # by the attached .weights, so this computes sum(diff * w * w):
+    # budget_impact = ((reform_tax - baseline_tax) * weight).sum()
+    budget_impact = (
+        (reform_tax.values - baseline_tax.values) * weight.values
+    ).sum()
+    budget_impact_m = budget_impact / 1e6
+
+    print(f"\nSC H.4216 budget impact: ${budget_impact_m:,.1f}M")
+    assert -130 < budget_impact_m < -110, (
+        f"Budget impact ${budget_impact_m:,.1f}M outside calibration target "
+        f"[-$130M, -$110M] (RFA fiscal note: -$119.1M)"
+    )