Apply Colorado, Connecticut, Illinois and Indiana rules for a filer who can be claimed as a dependent

changelog.d/claimable-filer-co-ct-il-in.fixed.md

@@ -0,0 +1 @@
+Apply Colorado, Connecticut, Illinois and Indiana rules for a filer who can be claimed as a dependent: no dependent-based credits, exemptions or deductions on such a return, and no childless EITC through the state ITIN and age extensions.

policyengine_us/reforms/states/il/dependent_exemption/il_dependent_exemption_reform.py

@@ -14,7 +14,13 @@ class il_dependent_exemption(Variable):
         def formula(tax_unit, period, parameters):
             p = parameters(period).gov.contrib.states.il.dependent_exemption
             person = tax_unit.members
-            is_dependent = person("is_tax_unit_dependent", period)
+            # A return on which the filer (or, if joint, either spouse) can be
+            # claimed as a dependent has no dependents (IRC 152(b)(1)), as in
+            # the baseline formula.
+            filer_is_dependent = person.tax_unit(
+                "head_or_spouse_is_dependent_elsewhere_without_filing_exception", period
+            )
+            is_dependent = person("is_tax_unit_dependent", period) & ~filer_is_dependent
             # Age gate: when in effect, restrict the exemption to dependents
             # under the chosen age; otherwise every dependent qualifies,
             # matching the baseline tax_unit_dependents count.

policyengine_us/reforms/states/in/dependent_exemption/in_dependent_exemption_reform.py

@@ -15,7 +15,13 @@ def formula(tax_unit, period, parameters):
 
             person = tax_unit.members
             age = person("age", period)
-            is_dependent = person("is_tax_unit_dependent", period)
+            # A return on which the filer (or, if joint, either spouse) can be
+            # claimed as a dependent has no dependents (IRC 152(b)(1)), as in
+            # the baseline formula.
+            filer_is_dependent = person.tax_unit(
+                "head_or_spouse_is_dependent_elsewhere_without_filing_exception", period
+            )
+            is_dependent = person("is_tax_unit_dependent", period) & ~filer_is_dependent
 
             # Apply age limit if in effect
             if p.age_limit.in_effect:
@@ -49,7 +55,12 @@ class in_older_dependents_count(Variable):
 
         def formula(tax_unit, period, parameters):
             person = tax_unit.members
-            is_dependent = person("is_tax_unit_dependent", period)
+            # Dependents barred by a claimable filer are not moved into the
+            # personal portion either.
+            filer_is_dependent = person.tax_unit(
+                "head_or_spouse_is_dependent_elsewhere_without_filing_exception", period
+            )
+            is_dependent = person("is_tax_unit_dependent", period) & ~filer_is_dependent
             total_dependents = tax_unit.sum(is_dependent)
             eligible_dependent_exemptions = tax_unit(
                 "in_eligible_dependents_count", period

policyengine_us/tests/core/test_claimable_filer_co_ct_il_in_invariants.py

@@ -0,0 +1,114 @@
+"""Colorado, Connecticut, Illinois and Indiana rules for a filer who can be
+claimed as a dependent.
+
+A return on which the filer, or on a joint return either spouse, can be claimed
+as a dependent has no dependents (IRC 152(b)(1)), so it gets no state
+dependent exemption or child-based deduction and no Colorado child credit, and
+a childless filer who can be claimed gets no state EITC through the ITIN or age
+extensions (IRC 32(c)(1)(A)(ii)(III)). Indiana keeps each filer's own $1,000
+exemption; Illinois' child tax credit follows the IRC 152 qualifying child.
+
+For couples drawn by Hypothesis and a seeded population in these states, with
+either, both or neither spouse claimed:
+
+1. Swap invariance: each output is the same under either head/spouse
+   labelling.
+2. Monotonicity: marking another filer as claimed never raises the outputs in
+   MONOTONE (amounts not capped by a tax liability that the claim can raise).
+3. Identities: a return with a claimable filer has no Illinois dependent
+   exemption, Colorado child tax credit or Indiana additional exemption, and
+   its Indiana base exemptions are $1,000 per filer.
+
+Hypothesis batches check 1 and 3; the seeded population checks 1, 2 and 3.
+"""
+
+import numpy as np
+import pytest
+from hypothesis import HealthCheck, given, settings
+from hypothesis import strategies as st
+
+from policyengine_us.tests.core.test_claimable_filer_federal_invariants import (
+    check_monotone,
+    check_swap,
+)
+from policyengine_us.tests.core.test_dependent_elsewhere_head_spouse_swap_invariance import (
+    CLAIM_PATTERNS,
+    _calc,
+    _crafted_cases,
+    _seeded_couples,
+    adults,
+    dependents,
+)
+
+STATES = ["CO", "CT", "IL", "IN"]
+YEARS = [2021, 2023, 2025, 2026]
+MONOTONE = [
+    "co_eitc",
+    "co_ctc",
+    "co_low_income_cdcc",
+    "ct_property_tax_credit_eligible",
+    "ct_child_tax_rebate",
+    "il_dependent_exemption",
+    "il_eitc",
+    "il_ctc",
+    "il_income_tax_rebate",
+    "il_income_tax_rebate_eligible",
+    "in_base_exemptions",
+    "in_additional_exemptions",
+    "in_adoption_exemption",
+]
+OUTPUTS = MONOTONE + ["co_refundable_credits"]
+
+
+@st.composite
+def couples(draw):
+    return {
+        "state": draw(st.sampled_from(STATES)),
+        "adults": [draw(adults()), draw(adults())],
+        "dependents": draw(st.lists(dependents(), max_size=2)),
+        "claimed": draw(st.sampled_from(CLAIM_PATTERNS)),
+    }
+
+
+def _identities(units):
+    states = np.array([unit["state"] for unit in units])
+
+    def check(sim, year):
+        claimed_filer = _calc(sim, "head_or_spouse_is_dependent_elsewhere", year) > 0
+        # Each unit is simulated as consecutive copies (labellings or claim
+        # patterns), in the order of the units.
+        state = np.repeat(states, len(claimed_filer) // len(units))
+        for name in (
+            "il_dependent_exemption",
+            "co_ctc",
+            "in_additional_exemptions",
+        ):
+            assert not _calc(sim, name, year)[claimed_filer].any(), (
+                f"{name} in {year} is positive on a return with a claimable filer"
+            )
+        filers = _calc(sim, "tax_unit_size", year) - _calc(
+            sim, "tax_unit_dependents", year
+        )
+        base = _calc(sim, "in_base_exemptions", year)
+        mask = claimed_filer & (state == "IN")
+        np.testing.assert_array_equal(base[mask], 1_000 * filers[mask])
+
+    return check
+
+
+@settings(
+    max_examples=2,
+    deadline=None,
+    derandomize=True,
+    suppress_health_check=[HealthCheck.too_slow, HealthCheck.data_too_large],
+)
+@given(st.sampled_from(YEARS), st.lists(couples(), min_size=6, max_size=12))
+def test_co_ct_il_in_claimable_filer_rules_are_label_free(year, units):
+    check_swap(units, year, OUTPUTS, _identities(units))
+
+
+@pytest.mark.parametrize("year", YEARS)
+def test_co_ct_il_in_claimable_filer_rules_seeded_population(year):
+    units = _seeded_couples(STATES, per_state=3) + _crafted_cases(STATES)
+    check_swap(units, year, OUTPUTS, _identities(units))
+    check_monotone(units, year, MONOTONE, _identities(units))

policyengine_us/tests/policy/baseline/gov/states/co/tax/income/credits/cdcc/co_cdcc.yaml

@@ -173,3 +173,146 @@
         state_code: CO
   output:
     co_cdcc: 0
+
+
+- name: 2025 single filer who can be claimed as a dependent, no Colorado child care credit for a child under 13
+  period: 2025
+  input:
+    people:
+      filer:
+        age: 30
+        employment_income: 50_000
+        is_tax_unit_head: true
+        is_tax_unit_spouse: false
+        claimed_as_dependent_on_another_return: true
+      child:
+        age: 2
+    tax_units:
+      tax_unit:
+        members: [filer, child]
+        tax_unit_childcare_expenses: 1_000
+    households:
+      household:
+        members: [filer, child]
+        state_code: CO
+  output:
+    # Already zero through the federal child care credit, which no
+    # longer counts a child under 13 on such a return.
+    co_cdcc: 0
+
+- name: 2025 joint return with one spouse who can be claimed as a dependent, no Colorado child care credit for a child under 13 (the claimable spouse is the head)
+  period: 2025
+  input:
+    people:
+      person_a:
+        age: 30
+        employment_income: 25_000
+        is_tax_unit_head: true
+        is_tax_unit_spouse: false
+        claimed_as_dependent_on_another_return: true
+      person_b:
+        age: 30
+        employment_income: 25_000
+        is_tax_unit_head: false
+        is_tax_unit_spouse: true
+      child:
+        age: 2
+    tax_units:
+      tax_unit:
+        members: [person_a, person_b, child]
+        filing_status: JOINT
+        tax_unit_childcare_expenses: 1_000
+    households:
+      household:
+        members: [person_a, person_b, child]
+        state_code: CO
+  output:
+    co_cdcc: 0
+
+- name: 2025 joint return with one spouse who can be claimed as a dependent, no Colorado child care credit for a child under 13 (the claimable spouse is the spouse)
+  period: 2025
+  input:
+    people:
+      person_b:
+        age: 30
+        employment_income: 25_000
+        is_tax_unit_head: true
+        is_tax_unit_spouse: false
+      person_a:
+        age: 30
+        employment_income: 25_000
+        is_tax_unit_head: false
+        is_tax_unit_spouse: true
+        claimed_as_dependent_on_another_return: true
+      child:
+        age: 2
+    tax_units:
+      tax_unit:
+        members: [person_b, person_a, child]
+        filing_status: JOINT
+        tax_unit_childcare_expenses: 1_000
+    households:
+      household:
+        members: [person_b, person_a, child]
+        state_code: CO
+  output:
+    co_cdcc: 0
+
+- name: 2025 joint return with both spouses claimable as dependents, no Colorado child care credit for a child under 13
+  period: 2025
+  input:
+    people:
+      person_a:
+        age: 30
+        employment_income: 25_000
+        is_tax_unit_head: true
+        is_tax_unit_spouse: false
+        claimed_as_dependent_on_another_return: true
+      person_b:
+        age: 30
+        employment_income: 25_000
+        is_tax_unit_head: false
+        is_tax_unit_spouse: true
+        claimed_as_dependent_on_another_return: true
+      child:
+        age: 2
+    tax_units:
+      tax_unit:
+        members: [person_a, person_b, child]
+        filing_status: JOINT
+        tax_unit_childcare_expenses: 1_000
+    households:
+      household:
+        members: [person_a, person_b, child]
+        state_code: CO
+  output:
+    co_cdcc: 0
+
+- name: 2025 joint return with neither spouse claimable, no Colorado child care credit for a child under 13
+  period: 2025
+  input:
+    people:
+      person_a:
+        age: 30
+        employment_income: 25_000
+        is_tax_unit_head: true
+        is_tax_unit_spouse: false
+      person_b:
+        age: 30
+        employment_income: 25_000
+        is_tax_unit_head: false
+        is_tax_unit_spouse: true
+      child:
+        age: 2
+    tax_units:
+      tax_unit:
+        members: [person_a, person_b, child]
+        filing_status: JOINT
+        tax_unit_childcare_expenses: 1_000
+    households:
+      household:
+        members: [person_a, person_b, child]
+        state_code: CO
+  output:
+    # Federal 20% x 1,000 = 200; Colorado 50% match = 100.
+    co_cdcc: 100