Divide monthly income by 4.33 weeks in New Hampshire's child care cost share

changelog.d/nh-ccap-cost-share-weeks.fixed.md

@@ -0,0 +1 @@
+Divide monthly income by 4.33 weeks in New Hampshire's child care cost share, as He-C 6910.18(b) directs.

policyengine_us/parameters/gov/states/nh/dhhs/ccap/cost_share/income_share_rate.yaml

@@ -18,7 +18,7 @@ metadata:
   label: New Hampshire CCAP income share rate by FPG ratio
   reference:
     - title: He-C 6910.18, Table 6910.19
-      href: https://www.law.cornell.edu/regulations/new-hampshire/N-H-Admin-Code-SS-He-C-6910.18
+      href: https://gc.nh.gov/rules/state_agencies/he-c6900.html
     - title: SR 24-08, Cost Share and Steps (January 2024)
       href: https://www.dhhs.nh.gov/sr_htm/html/sr_24-08_dated_01_24.htm
     - title: New Hampshire CCDF State Plan 2025-2027, Section 3.2.1

policyengine_us/parameters/gov/states/nh/dhhs/ccap/cost_share/weekly_flat_amount.yaml

@@ -22,7 +22,7 @@ metadata:
   label: New Hampshire CCAP weekly flat cost share amount by FPG ratio
   reference:
     - title: He-C 6910.18, Table 6910.19
-      href: https://www.law.cornell.edu/regulations/new-hampshire/N-H-Admin-Code-SS-He-C-6910.18
+      href: https://gc.nh.gov/rules/state_agencies/he-c6900.html
     - title: SR 24-08, Cost Share and Steps (January 2024)
       href: https://www.dhhs.nh.gov/sr_htm/html/sr_24-08_dated_01_24.htm
     - title: New Hampshire CCDF State Plan 2025-2027, Section 3.2.1

policyengine_us/parameters/gov/states/nh/dhhs/ccap/cost_share/weeks_per_month.yaml

@@ -0,0 +1,14 @@
+description: New Hampshire divides monthly income by this number of weeks to calculate the weekly family cost share under the Child Care Scholarship Program.
+
+values:
+  2020-07-01: 4.33
+
+metadata:
+  unit: week
+  period: month
+  label: New Hampshire CCAP weeks per month for the family cost share
+  reference:
+    - title: He-C 6910.18(b)
+      href: https://gc.nh.gov/rules/state_agencies/he-c6900.html
+    - title: He-C 6910.18(d) (effective July 1, 2020)
+      href: https://www.law.cornell.edu/regulations/new-hampshire/N-H-Admin-Code-SS-He-C-6910.18

policyengine_us/tests/policy/baseline/gov/states/nh/dhhs/ccap/integration.yaml

@@ -100,7 +100,7 @@
         weekly_hours_worked_before_lsr: 40
         employment_income: 60_000
         # $60,000/yr = $5,000/mo > $3,064.75 (138% FPG for 3)
-        # Step 3: 7% * $5,000 / 4.33 = $80.77/week
+        # Step 3: 7% * $5,000 / 4.33 = $80.83/week
       person2:
         age: 35
         weekly_hours_worked_before_lsr: 40
@@ -129,8 +129,8 @@
     nh_ccap_income_eligible: true
     nh_ccap_eligible: true
 
-    # Cost share: 7% * $5,000 / (52/12) = $350 / 4.3333 = $80.77/week
-    nh_ccap_cost_share: 80.77
+    # Cost share: 7% * $5,000 / 4.33 = $350 / 4.33 = $80.83/week
+    nh_ccap_cost_share: 80.83
 
 - name: Case 4, two eligible children, cost share split equally.
   period: 2025-01
@@ -379,3 +379,44 @@
     nh_ccap_income_eligible: false
     nh_ccap_eligible: false
     nh_ccap: 0
+
+- name: Case 10, positive benefit end-to-end at step 3, the cost share divides by 4.33 weeks.
+  period: 2025-01
+  absolute_error_margin: 0.01
+  input:
+    people:
+      person1:
+        age: 28
+        weekly_hours_worked_before_lsr: 40
+        employment_income: 48_000
+        # $48,000/yr = $4,000/mo, above 138% of the 2024 poverty guideline for 2 ($2,350.60),
+        # which He-C 6910.18(e) applies until July 2025, and of the 2025 guideline ($2,432.25),
+        # which the model applies from January. Below 85% SMI for 2 ($7,060.37).
+      person2:
+        age: 4
+        is_tax_unit_dependent: true
+        immigration_status: CITIZEN
+        childcare_hours_per_week: 40
+        nh_ccap_provider_type: LICENSED_CENTER
+        pre_subsidy_childcare_expenses: 18_720
+        # $18,720/yr = $360/week
+    spm_units:
+      spm_unit:
+        members: [person1, person2]
+
+    tax_units:
+      tax_unit:
+        members: [person1, person2]
+    households:
+      household:
+        members: [person1, person2]
+        state_code: NH
+  output:
+    nh_ccap_eligible: true
+    # Cost share: 7% * $4,000 / 4.33 = $280 / 4.33 = $64.67/week
+    nh_ccap_cost_share: 64.67
+    # Preschool, full-time, licensed center: $280/week
+    # min($360/wk charge, $280 rate) = $280
+    # Weekly payment: $280 - $280 / 4.33 = $215.3349
+    # Monthly: $215.3349 * (52/12) = $933.12
+    nh_ccap: 933.12

policyengine_us/tests/policy/baseline/gov/states/nh/dhhs/ccap/nh_ccap_cost_share.yaml

@@ -5,7 +5,7 @@
 # 2025 FPG family of 3: 15,650 + 5,500*2 = $26,650/year = $2,220.83/month
 # Step 1: <= 100% FPG ($2,220.83/mo) → $0/week
 # Step 2: > 100% to <= 138% FPG ($3,064.75/mo) → $5/week
-# Step 3: > 138% FPG → 7% * monthly income / (52/12)
+# Step 3: > 138% FPG → 7% * monthly income / 4.33
 #
 # 2025 FPG family of 2: 15,650 + 5,500 = $21,150/year = $1,762.50/month
 # 2025 FPG family of 1: $15,650/year = $1,304.17/month
@@ -66,7 +66,7 @@
         age: 30
         employment_income: 53_304
         # $53,304/yr = $4,442/mo > $3,064.75 (138% FPG)
-        # Step 3: 7% * $4,442 / (52/12) = $71.77/week
+        # Step 3: 7% * $4,442 / 4.33 = $71.81/week
       person2:
         age: 5
       person3:
@@ -79,8 +79,8 @@
         members: [person1, person2, person3]
         state_code: NH
   output:
-    # $4,442 * 0.07 / (52/12) = $310.94 / 4.3333 = $71.76
-    nh_ccap_cost_share: 71.76
+    # $4,442 * 0.07 / 4.33 = $310.94 / 4.33 = $71.81
+    nh_ccap_cost_share: 71.81
 
 - name: Case 4, income exactly at 100% FPG boundary, step 1.
   period: 2025-01
@@ -175,8 +175,8 @@
         state_code: NH
   output:
     # $2,433.33 * 0.07 = $170.33
-    # $170.33 / (52/12) = $170.33 / 4.3333 = $39.31
-    nh_ccap_cost_share: 39.31
+    # $170.33 / 4.33 = $39.34
+    nh_ccap_cost_share: 39.34
 
 - name: Case 8, zero income, step 1, $0 cost share.
   period: 2025-01

policyengine_us/tests/test_nh_ccap_cost_share_properties.py

@@ -0,0 +1,110 @@
+"""Invariants of New Hampshire's child care family cost share, He-C 6910.18.
+
+1. Step 1: a family at or below 100% of the poverty guidelines owes nothing.
+2. Step 2: a family above 100% and at or below 138% owes $5 a week.
+3. Step 3: a family above 138% owes 7% of monthly income divided by 4.33 weeks,
+   and within the step the share rises with income.
+4. For a family with one eligible child and no disability supplement, the
+   monthly payment equals 52/12 weeks of the lesser of the charge and the standard
+   rate, less the cost share, floored at zero.
+
+rule_cost_share restates the rule's table on its own, so the variable and the
+table must agree. The YAML cases pin single families; these draw incomes and
+charges across the steps.
+"""
+
+from hypothesis import assume, example, given, settings
+from hypothesis import strategies as st
+import pytest
+
+from policyengine_us import Simulation
+
+YEAR = 2025
+# He-C 6910.18(e) applies each year's poverty guidelines from the following July,
+# so July 2025 uses the 2025 guideline for a family of two.
+MONTH = "2025-07"
+FPG = 21_150
+WEEKLY_RATE = 280  # Preschool, full time, licensed center.
+TOLERANCE = 0.01
+
+
+def rule_cost_share(annual_income):
+    if annual_income <= FPG:
+        return 0
+    if annual_income * 100 <= FPG * 138:
+        return 5
+    return annual_income / 12 * 0.07 / 4.33
+
+
+def outside_boundary_slivers(annual_income):
+    # The parameters place the steps at 1.0001 and 1.3801 of the guideline, so a
+    # family inside those slivers takes the lower step.
+    # Integer cross-products keep 138% of the guideline, $29,187, out of the sliver.
+    in_first = FPG * 10_000 < annual_income * 10_000 < FPG * 10_001
+    in_second = FPG * 13_800 < annual_income * 10_000 < FPG * 13_801
+    return not (in_first or in_second)
+
+
+def cost_share_and_payment(annual_income, annual_charge):
+    members = ["parent", "child"]
+    parent = {
+        "age": {YEAR: 28},
+        "weekly_hours_worked_before_lsr": {YEAR: 40},
+        "employment_income": {YEAR: annual_income},
+    }
+    child = {
+        "age": {YEAR: 4},
+        "is_tax_unit_dependent": {YEAR: True},
+        "immigration_status": {YEAR: "CITIZEN"},
+        "childcare_hours_per_week": {YEAR: 40},
+        "nh_ccap_provider_type": {YEAR: "LICENSED_CENTER"},
+        "pre_subsidy_childcare_expenses": {YEAR: annual_charge},
+    }
+    situation = {
+        "people": {"parent": parent, "child": child},
+        "tax_units": {"tax_unit": {"members": members}},
+        "spm_units": {"spm_unit": {"members": members}},
+        "families": {"family": {"members": members}},
+        "marital_units": {"marital_unit": {"members": ["parent"]}},
+        "households": {"household": {"members": members, "state_name": {YEAR: "NH"}}},
+    }
+    simulation = Simulation(situation=situation)
+    return [
+        float(simulation.calculate(name, MONTH)[0])
+        for name in ("nh_ccap_cost_share", "nh_ccap")
+    ]
+
+
+@settings(max_examples=15, deadline=None)
+# Zero income, each step's upper edge, the first dollars above 138%, and a charge
+# below the rate that the cost share exceeds.
+@example(annual_income=0, annual_charge=18_720)
+@example(annual_income=FPG, annual_charge=18_720)
+@example(annual_income=FPG * 138 // 100, annual_charge=18_720)
+@example(annual_income=29_200, annual_charge=18_720)
+@example(annual_income=48_000, annual_charge=18_720)
+@example(annual_income=80_000, annual_charge=1_000)
+@given(
+    annual_income=st.integers(min_value=0, max_value=80_000),
+    annual_charge=st.integers(min_value=1, max_value=40_000),
+)
+def test_cost_share_and_payment_follow_the_rule(annual_income, annual_charge):
+    assume(outside_boundary_slivers(annual_income))
+    share, payment = cost_share_and_payment(annual_income, annual_charge)
+    expected_share = rule_cost_share(annual_income)
+    assert share == pytest.approx(expected_share, abs=TOLERANCE)
+    weekly_cap = min(annual_charge / 52, WEEKLY_RATE)
+    expected_payment = max(weekly_cap - expected_share, 0) * 52 / 12
+    assert payment == pytest.approx(expected_payment, abs=TOLERANCE)
+
+
+@settings(max_examples=10, deadline=None)
+@given(
+    lower=st.integers(min_value=29_190, max_value=79_999),
+    gap=st.integers(min_value=1, max_value=20_000),
+)
+def test_step_three_share_rises_with_income(lower, gap):
+    higher = min(lower + gap, 80_000)
+    lower_share, _ = cost_share_and_payment(lower, 18_720)
+    higher_share, _ = cost_share_and_payment(higher, 18_720)
+    assert higher_share > lower_share

policyengine_us/variables/gov/states/nh/dhhs/ccap/nh_ccap_cost_share.py

@@ -9,18 +9,17 @@ class nh_ccap_cost_share(Variable):
     definition_period = MONTH
     defined_for = StateCode.NH
     reference = (
-        "https://www.law.cornell.edu/regulations/new-hampshire/N-H-Admin-Code-SS-He-C-6910.18",
+        "https://gc.nh.gov/rules/state_agencies/he-c6900.html",
         "https://www.dhhs.nh.gov/sr_htm/html/sr_24-08_dated_01_24.htm",
     )
 
     def formula(spm_unit, period, parameters):
         p = parameters(period).gov.states.nh.dhhs.ccap.cost_share
         countable_income = spm_unit("nh_ccap_countable_income", period)
         fpg = spm_unit("spm_unit_fpg", period)
-        weeks_per_month = WEEKS_IN_YEAR / MONTHS_IN_YEAR
 
         fpg_ratio = where(fpg > 0, countable_income / fpg, 0)
         income_based_share = (
-            countable_income * p.income_share_rate.calc(fpg_ratio) / weeks_per_month
+            countable_income * p.income_share_rate.calc(fpg_ratio) / p.weeks_per_month
         )
         return p.weekly_flat_amount.calc(fpg_ratio) + income_based_share