Add South Carolina fully refundable EITC contrib reform

changelog.d/sc-fully-refundable-eitc-reform.added.md

@@ -0,0 +1 @@
+Added a South Carolina fully refundable EITC contrib reform for the Child Poverty Impact Dashboard.

policyengine_us/parameters/gov/contrib/states/sc/child_poverty_impact_dashboard/eitc/in_effect.yaml

@@ -0,0 +1,9 @@
+description: South Carolina applies a fully refundable EITC when this parameter is in effect. By default, the SC EITC is nonrefundable. This reform makes it refundable for ALL filers.
+
+values:
+  0000-01-01: false
+
+metadata:
+  unit: bool
+  period: year
+  label: South Carolina fully refundable EITC in effect

policyengine_us/reforms/reforms.py

@@ -263,6 +263,9 @@
 from .states.ut.child_poverty_eitc import (
     create_ut_fully_refundable_eitc_reform,
 )
+from .states.sc.child_poverty_eitc import (
+    create_sc_fully_refundable_eitc_reform,
+)
 from policyengine_core.reforms import Reform
 import warnings
 
@@ -455,6 +458,9 @@ def create_structural_reforms_from_parameters(parameters, period):
     ut_fully_refundable_eitc = create_ut_fully_refundable_eitc_reform(
         parameters, period
     )
+    sc_fully_refundable_eitc = create_sc_fully_refundable_eitc_reform(
+        parameters, period
+    )
     nj_stay_nj = create_nj_stay_nj_reform(parameters, period)
     nj_anchor = create_nj_anchor_reform(parameters, period)
     working_parents_tax_relief_act = create_working_parents_tax_relief_act_reform(
@@ -570,6 +576,7 @@ def create_structural_reforms_from_parameters(parameters, period):
         mo_refundable_eitc,
         oh_refundable_eitc,
         ut_fully_refundable_eitc,
+        sc_fully_refundable_eitc,
         nj_stay_nj,
         nj_anchor,
         working_parents_tax_relief_act,

policyengine_us/reforms/states/sc/child_poverty_eitc/__init__.py

@@ -0,0 +1,5 @@
+from .sc_fully_refundable_eitc_reform import (
+    create_sc_fully_refundable_eitc,
+    create_sc_fully_refundable_eitc_reform,
+    sc_fully_refundable_eitc,
+)

policyengine_us/reforms/states/sc/child_poverty_eitc/sc_fully_refundable_eitc_reform.py

@@ -0,0 +1,125 @@
+from policyengine_us.model_api import *
+from policyengine_core.periods import period as period_
+from policyengine_us.variables.gov.states.tax.income.non_refundable_credit_cap import (
+    ordered_capped_state_non_refundable_credits,
+)
+
+
+def create_sc_fully_refundable_eitc() -> Reform:
+    """
+    South Carolina Fully Refundable EITC Reform
+
+    Converts the South Carolina EITC from nonrefundable to fully refundable
+    for ALL filers. SC's EITC is 125% of the federal EITC (subject to a
+    per-filer cap — $200 from 2026) and is nonrefundable by default, i.e.
+    applied only up to remaining state income tax liability. This reform pays
+    the potential (uncapped-at-liability) credit as a refundable credit, so
+    zero-liability filers receive it.
+
+    Mirrors the corrected Utah/Missouri/Ohio refundability reforms
+    (PolicyEngine/policyengine-us#8645, #8642, #8657): pay the ``*_potential``
+    amount, rebuild the non-refundable bucket with the EITC filtered out of
+    the ordered cap walk, and clear the inherited ``adds`` on the refundable
+    aggregate before giving it a formula.
+
+    Activated by
+    ``gov.contrib.states.sc.child_poverty_impact_dashboard.eitc.in_effect``.
+
+    Reference: SC Code Section 12-6-3632.
+    """
+
+    class sc_fully_refundable_eitc(Variable):
+        value_type = float
+        entity = TaxUnit
+        label = "South Carolina fully refundable EITC"
+        unit = USD
+        definition_period = YEAR
+        defined_for = StateCode.SC
+
+        def formula(tax_unit, period, parameters):
+            # Pay the potential (uncapped-at-liability) SC EITC so the whole
+            # credit is refundable; ``sc_eitc`` is capped at tax liability and
+            # would zero out for the low-liability filers refundability is
+            # meant to help. ``sc_eitc_potential`` still applies the statutory
+            # per-filer cap (gov.states.sc.tax.income.credits.eitc.max).
+            return tax_unit("sc_eitc_potential", period)
+
+    class sc_non_refundable_credits(Variable):
+        value_type = float
+        entity = TaxUnit
+        label = "South Carolina non-refundable credits"
+        unit = USD
+        definition_period = YEAR
+        defined_for = StateCode.SC
+
+        def formula(tax_unit, period, parameters):
+            # Mirror the baseline ordered-cap walk but drop sc_eitc from the
+            # non-refundable bucket — it is paid as a refundable credit under
+            # this reform. A raw ``sum - sc_eitc`` would overstate the total
+            # whenever the bucket binds at liability, so re-run the ordered
+            # walk over the filtered list instead.
+            ordered_credits = parameters(
+                period
+            ).gov.states.sc.tax.income.credits.non_refundable
+            filtered_credits = [
+                credit for credit in list(ordered_credits) if credit != "sc_eitc"
+            ]
+            return ordered_capped_state_non_refundable_credits(
+                tax_unit,
+                period,
+                filtered_credits,
+                "sc_income_tax_before_non_refundable_credits",
+            )
+
+    class sc_refundable_credits(Variable):
+        value_type = float
+        entity = TaxUnit
+        label = "South Carolina refundable credits"
+        unit = USD
+        definition_period = YEAR
+        defined_for = StateCode.SC
+        # The baseline computes via ``adds``. We replace it with a formula, so
+        # clear the inherited computation modes to avoid mixing ``formula``
+        # with ``adds``/``subtracts`` (rejected by the core engine).
+        adds = None
+        subtracts = None
+
+        def formula(tax_unit, period, parameters):
+            p = parameters(period).gov.states.sc.tax.income.credits
+            standard_credits = add(tax_unit, period, p.refundable)
+            refundable_eitc = tax_unit("sc_fully_refundable_eitc", period)
+            return standard_credits + refundable_eitc
+
+    class reform(Reform):
+        def apply(self):
+            self.update_variable(sc_fully_refundable_eitc)
+            self.update_variable(sc_non_refundable_credits)
+            self.update_variable(sc_refundable_credits)
+
+    return reform
+
+
+def create_sc_fully_refundable_eitc_reform(parameters, period, bypass: bool = False):
+    if bypass:
+        return create_sc_fully_refundable_eitc()
+
+    p = parameters.gov.contrib.states.sc.child_poverty_impact_dashboard.eitc
+
+    reform_active = False
+    current_period = period_(period)
+
+    for i in range(5):
+        if p(current_period).in_effect:
+            reform_active = True
+            break
+        current_period = current_period.offset(1, "year")
+
+    if reform_active:
+        return create_sc_fully_refundable_eitc()
+    else:
+        return None
+
+
+sc_fully_refundable_eitc = create_sc_fully_refundable_eitc_reform(
+    None, None, bypass=True
+)

policyengine_us/tests/code_health/test_non_refundable_credit_downstream_consumers.py

@@ -31,6 +31,9 @@
     "sc_cdcc": {
         "reforms/states/sc/h3492/sc_h3492_eitc_refundable.py",
     },
+    "sc_eitc": {
+        "reforms/states/sc/child_poverty_eitc/sc_fully_refundable_eitc_reform.py",
+    },
     "sc_two_wage_earner_credit": {
         "reforms/states/sc/h3492/sc_h3492_eitc_refundable.py",
     },

policyengine_us/tests/policy/reform/sc_fully_refundable_eitc.yaml

@@ -0,0 +1,62 @@
+# Tests for the South Carolina fully refundable EITC contrib reform.
+#
+# The reform converts SC's nonrefundable EITC (125% of the federal EITC, capped
+# per filer at $200 from 2026) to fully refundable for all filers. It pays the
+# potential (uncapped-at-liability) credit, so zero-liability filers receive it.
+# These tests drive the credit from the federal EITC and pin SC tax liability
+# directly. Mirrors the corrected UT/MO/OH reforms (issues #8644/#8640/#8656).
+
+- name: Pays the full potential SC EITC as a refundable credit at zero liability
+  period: 2026
+  reforms: policyengine_us.reforms.states.sc.child_poverty_eitc.sc_fully_refundable_eitc_reform.sc_fully_refundable_eitc
+  input:
+    state_code: SC
+    eitc: 100
+    # Pin SC tax liability to zero so the nonrefundable cap binds at $0 — the
+    # test is whether the reform pays the credit despite no liability.
+    sc_income_tax_before_non_refundable_credits: 0
+  output:
+    # 2026 SC EITC is 125% of the federal EITC: 100 * 1.25 = 125, below the
+    # $200 per-filer cap.
+    sc_eitc_potential: 125
+    # The capped credit is 0 at zero liability; the reform pays the uncapped
+    # potential instead — the whole point of the conversion.
+    sc_eitc: 0
+    # Paid in full as refundable, even with no SC tax liability.
+    sc_fully_refundable_eitc: 125
+    sc_refundable_credits: 125
+
+- name: Does not double count when liability could absorb the EITC
+  period: 2026
+  reforms: policyengine_us.reforms.states.sc.child_poverty_eitc.sc_fully_refundable_eitc_reform.sc_fully_refundable_eitc
+  input:
+    state_code: SC
+    eitc: 100
+    sc_income_tax_before_non_refundable_credits: 1_000
+  output:
+    sc_fully_refundable_eitc: 125
+    # EITC is removed from the non-refundable bucket (no other SC credits here).
+    sc_non_refundable_credits: 0
+    sc_refundable_credits: 125
+
+- name: Respects the statutory per-filer cap ($200 in 2026)
+  period: 2026
+  reforms: policyengine_us.reforms.states.sc.child_poverty_eitc.sc_fully_refundable_eitc_reform.sc_fully_refundable_eitc
+  input:
+    state_code: SC
+    eitc: 1_000
+    sc_income_tax_before_non_refundable_credits: 0
+  output:
+    # 1,000 * 1.25 = 1,250, capped at the $200 maximum.
+    sc_eitc_potential: 200
+    sc_fully_refundable_eitc: 200
+    sc_refundable_credits: 200
+
+- name: No effect outside South Carolina
+  period: 2026
+  reforms: policyengine_us.reforms.states.sc.child_poverty_eitc.sc_fully_refundable_eitc_reform.sc_fully_refundable_eitc
+  input:
+    state_code: CA
+    eitc: 100
+  output:
+    sc_fully_refundable_eitc: 0