Add NY A04038 Enhanced Empire State Child Credit for Infants Act reform

Implements Assembly Bill A04038 which doubles the Empire State Child Credit
for qualifying children under age one, effective tax year 2026.

Closes #7181

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Author: DTrim99

changelog_entry.yaml

@@ -0,0 +1,4 @@
+- bump: minor
+  changes:
+    added:
+    - NY A04038 Enhanced Empire State Child Credit for Infants Act reform.

policyengine_us/parameters/gov/contrib/states/ny/a04038/in_effect.yaml

@@ -0,0 +1,10 @@
+description: The New York Enhanced Empire State Child Credit for Infants Act (Assembly Bill A04038) applies if this is true.
+metadata:
+  unit: bool
+  period: year
+  label: NY A04038 Enhanced Empire State Child Credit for Infants in effect
+  reference:
+    - title: NY Assembly Bill 2025-A04038
+      href: https://assembly.state.ny.us/leg/?default_fld=&bn=A04038&term=2025&Summary=Y&Actions=Y&Text=Y
+values:
+  0000-01-01: false

policyengine_us/parameters/gov/contrib/states/ny/a04038/multiplier.yaml

@@ -0,0 +1,20 @@
+description: New York multiplies the Empire State Child Credit by this amount based on the child's age under the Enhanced Empire State Child Credit for Infants Act.
+metadata:
+  type: single_amount
+  threshold_unit: year
+  amount_unit: /1
+  label: NY A04038 infant child credit multiplier
+  period: year
+  reference:
+    - title: NY Assembly Bill 2025-A04038
+      href: https://assembly.state.ny.us/leg/?default_fld=&bn=A04038&term=2025&Summary=Y&Actions=Y&Text=Y
+
+brackets:
+  - threshold:
+      2026-01-01: 0
+    amount:
+      2026-01-01: 2  # Double for children under age 1
+  - threshold:
+      2026-01-01: 1
+    amount:
+      2026-01-01: 1  # Standard credit for children age 1+

policyengine_us/reforms/reforms.py

@@ -20,6 +20,7 @@
 from .biden.budget_2025 import create_capital_gains_tax_increase_reform
 from .eitc import create_halve_joint_eitc_phase_out_rate_reform
 from .states.ny.wftc import create_ny_working_families_tax_credit_reform
+from .states.ny.a04038 import create_ny_a04038_enhanced_escc_infants_reform
 from .states.sc.h3492 import create_sc_h3492_eitc_refundable_reform
 from .harris.lift.middle_class_tax_credit import (
     create_middle_class_tax_credit_reform,
@@ -179,6 +180,9 @@ def create_structural_reforms_from_parameters(parameters, period):
         create_halve_joint_eitc_phase_out_rate_reform(parameters, period)
     )
     ny_wftc = create_ny_working_families_tax_credit_reform(parameters, period)
+    ny_a04038_enhanced_escc_infants = (
+        create_ny_a04038_enhanced_escc_infants_reform(parameters, period)
+    )
     sc_h3492_eitc_refundable = create_sc_h3492_eitc_refundable_reform(
         parameters, period
     )
@@ -327,6 +331,7 @@ def create_structural_reforms_from_parameters(parameters, period):
         capital_gains_tax_increase,
         halve_joint_eitc_phase_out_rate,
         ny_wftc,
+        ny_a04038_enhanced_escc_infants,
         sc_h3492_eitc_refundable,
         middle_class_tax_credit,
         rent_relief_tax_credit,

policyengine_us/reforms/states/ny/a04038/__init__.py

@@ -0,0 +1,3 @@
+from .ny_a04038_enhanced_escc_infants import (
+    create_ny_a04038_enhanced_escc_infants_reform,
+)

policyengine_us/reforms/states/ny/a04038/ny_a04038_enhanced_escc_infants.py

@@ -0,0 +1,76 @@
+from policyengine_us.model_api import *
+
+
+def create_ny_a04038_enhanced_escc_infants() -> Reform:
+    """
+    NY Assembly Bill A04038 - Enhanced Empire State Child Credit for Infants Act
+
+    Doubles the Empire State Child Credit for qualifying children under age one,
+    effective tax year 2026 and thereafter.
+
+    Reference: https://assembly.state.ny.us/leg/?default_fld=&bn=A04038&term=2025
+    """
+
+    class ny_ctc_post_2024_base(Variable):
+        value_type = float
+        entity = TaxUnit
+        label = "New York CTC post-2024 base amount"
+        documentation = (
+            "Base New York CTC amount before phase-out under post-2024 rules"
+        )
+        unit = USD
+        definition_period = YEAR
+        reference = (
+            "https://assembly.state.ny.us/leg/?default_fld=&bn=A04038&term=2025",
+            "https://www.nysenate.gov/legislation/laws/TAX/606",
+        )
+        defined_for = "ny_ctc_post_2024_eligible"
+
+        def formula(tax_unit, period, parameters):
+            p = parameters(period).gov.states.ny.tax.income.credits.ctc
+            p_reform = parameters(period).gov.contrib.states.ny.a04038
+            person = tax_unit.members
+            age = person("age", period)
+
+            # Post-2024 CTC rules (2025-2027)
+            qualifies_for_federal_ctc = person("ctc_qualifying_child", period)
+            qualifies = qualifies_for_federal_ctc & (age >= p.minimum_age)
+
+            # Calculate base credit amount by age
+            credit_by_age = p.post_2024.amount.calc(age)
+
+            # Apply infant multiplier if reform is in effect
+            multiplier = where(
+                p_reform.in_effect,
+                p_reform.multiplier.calc(age),
+                1,
+            )
+
+            qualifying_credit = qualifies * credit_by_age * multiplier
+
+            return tax_unit.sum(qualifying_credit)
+
+    class reform(Reform):
+        def apply(self):
+            self.update_variable(ny_ctc_post_2024_base)
+
+    return reform
+
+
+def create_ny_a04038_enhanced_escc_infants_reform(
+    parameters, period, bypass: bool = False
+):
+    if bypass:
+        return create_ny_a04038_enhanced_escc_infants()
+
+    p = parameters(period).gov.contrib.states.ny.a04038
+
+    if p.in_effect:
+        return create_ny_a04038_enhanced_escc_infants()
+    else:
+        return None
+
+
+ny_a04038_enhanced_escc_infants = (
+    create_ny_a04038_enhanced_escc_infants_reform(None, None, bypass=True)
+)

policyengine_us/tests/policy/contrib/states/ny/a04038/ny_a04038_enhanced_escc_infants.yaml

@@ -0,0 +1,137 @@
+# NY A04038 Enhanced Empire State Child Credit for Infants Act Tests
+# Tests the doubled CTC for children under age 1, effective 2026
+
+# Basic test - infant (age 0) gets doubled credit
+- name: Infant under age 1 gets doubled credit
+  period: 2026
+  reforms: policyengine_us.reforms.states.ny.a04038.ny_a04038_enhanced_escc_infants.ny_a04038_enhanced_escc_infants
+  input:
+    gov.contrib.states.ny.a04038.in_effect: true
+    people:
+      person1:
+        age: 35
+        is_tax_unit_head: true
+        employment_income: 50_000
+      infant:
+        age: 0
+        is_tax_unit_dependent: true
+    tax_units:
+      tax_unit:
+        members: [person1, infant]
+    households:
+      household:
+        members: [person1, infant]
+        state_code: NY
+  output:
+    # Base credit for ages 0-3 in 2026 is $1,000
+    # Doubled for infant: $1,000 * 2 = $2,000
+    ny_ctc_post_2024_base: 2_000
+
+# Child age 1 gets standard credit (no doubling)
+- name: Child age 1 gets standard credit
+  period: 2026
+  reforms: policyengine_us.reforms.states.ny.a04038.ny_a04038_enhanced_escc_infants.ny_a04038_enhanced_escc_infants
+  input:
+    gov.contrib.states.ny.a04038.in_effect: true
+    people:
+      person1:
+        age: 35
+        is_tax_unit_head: true
+        employment_income: 50_000
+      child:
+        age: 1
+        is_tax_unit_dependent: true
+    tax_units:
+      tax_unit:
+        members: [person1, child]
+    households:
+      household:
+        members: [person1, child]
+        state_code: NY
+  output:
+    # Base credit for ages 0-3 in 2026 is $1,000
+    # Age 1 does not qualify for doubling: $1,000 * 1 = $1,000
+    ny_ctc_post_2024_base: 1_000
+
+# Mixed ages - infant and older child
+- name: Mixed ages - infant doubled, older child standard
+  period: 2026
+  reforms: policyengine_us.reforms.states.ny.a04038.ny_a04038_enhanced_escc_infants.ny_a04038_enhanced_escc_infants
+  input:
+    gov.contrib.states.ny.a04038.in_effect: true
+    people:
+      person1:
+        age: 35
+        is_tax_unit_head: true
+        employment_income: 50_000
+      infant:
+        age: 0
+        is_tax_unit_dependent: true
+      child:
+        age: 5
+        is_tax_unit_dependent: true
+    tax_units:
+      tax_unit:
+        members: [person1, infant, child]
+    households:
+      household:
+        members: [person1, infant, child]
+        state_code: NY
+  output:
+    # Infant (age 0): $1,000 * 2 = $2,000
+    # Child (age 5): $500 * 1 = $500 (ages 4-16 get $500 in 2026)
+    # Total: $2,500
+    ny_ctc_post_2024_base: 2_500
+
+# Reform not in effect - standard credit
+- name: Reform not in effect uses standard credit
+  period: 2026
+  reforms: policyengine_us.reforms.states.ny.a04038.ny_a04038_enhanced_escc_infants.ny_a04038_enhanced_escc_infants
+  input:
+    gov.contrib.states.ny.a04038.in_effect: false
+    people:
+      person1:
+        age: 35
+        is_tax_unit_head: true
+        employment_income: 50_000
+      infant:
+        age: 0
+        is_tax_unit_dependent: true
+    tax_units:
+      tax_unit:
+        members: [person1, infant]
+    households:
+      household:
+        members: [person1, infant]
+        state_code: NY
+  output:
+    # Without reform, infant gets standard $1,000
+    ny_ctc_post_2024_base: 1_000
+
+# Two infants get doubled credits
+- name: Two infants both get doubled credits
+  period: 2026
+  reforms: policyengine_us.reforms.states.ny.a04038.ny_a04038_enhanced_escc_infants.ny_a04038_enhanced_escc_infants
+  input:
+    gov.contrib.states.ny.a04038.in_effect: true
+    people:
+      person1:
+        age: 35
+        is_tax_unit_head: true
+        employment_income: 50_000
+      infant1:
+        age: 0
+        is_tax_unit_dependent: true
+      infant2:
+        age: 0
+        is_tax_unit_dependent: true
+    tax_units:
+      tax_unit:
+        members: [person1, infant1, infant2]
+    households:
+      household:
+        members: [person1, infant1, infant2]
+        state_code: NY
+  output:
+    # Two infants: $1,000 * 2 * 2 = $4,000
+    ny_ctc_post_2024_base: 4_000