Illinois Home Weatherization Assistance Program (IHWAP)

[hua7450]

Summary

Closes #6779

Adds eligibility determination for the Illinois Home Weatherization Assistance Program (IHWAP), a federally-funded, state-administered program that provides free weatherization services to income-eligible households.

Regulatory Authority

• 42 U.S.C. 6862(7) - Federal WAP low-income definition
• 42 U.S.C. 8624(b)(2) - LIHEAP "greater of" income threshold rule
• Illinois DCEO Home Weatherization Program

Income Eligibility

Per IL DCEO guidelines:

• Sizes 1-7: Income ≤ 200% FPL (all funding sources use same threshold)
• Sizes 8+: Income ≤ max(200% FPL, 60% SMI) (two columns in IL DCEO table)

Income Standards (Illinois, PY2026)

Household Size	200% FPL	60% SMI	Threshold
1	$31,300	—	$31,300
2	$42,300	—	$42,300
3	$53,300	—	$53,300
4	$64,300	—	$64,300
5	$75,300	—	$75,300
6	$86,300	—	$86,300
7	$97,300	—	$97,300
8	$108,300	$106,100	$108,300
9	$119,300	$108,406	$119,300
10	$130,300	$110,713	$130,300
11	$141,300	$113,019	$141,300
12	$152,300	$115,326	$152,300

For sizes 8+, 200% FPL is higher than 60% SMI, so FPL is the effective threshold.

⚠️ Special Period Handling

IL IHWAP Program Year N uses FPL/SMI values from year N-1.

PolicyEngine Period	IL DCEO Program Year	FPL Source	SMI Source
2026	PY2026	2025-01-01	2025-10-01
2027	PY2027	2026-01-01	2026-10-01

Implementation

• FPL: Uses reusable fpg() function with prior_year period string
• SMI: Uses custom il_ihwap_hhs_smi variable that accesses SMI parameters at the specific October 1 instant ({year-1}-10-01)

This approach is necessary because SMI parameters update on October 1, so accessing by year alone would give incorrect values.

Categorical Eligibility

A household automatically qualifies if any member receives:

• IL LIHEAP - 42 U.S.C. 6862(7)(B)
• SSI - 42 U.S.C. 6862(7)(B) → 42 U.S.C. 1381 (Title XVI SSA)
• IL TANF - 42 U.S.C. 6862(7)(B) → 42 U.S.C. 601 (Title IV SSA)
• IL AABD - 42 U.S.C. 6862(7)(B) ("applicable State or local law")
• HUD housing assistance - Section 8, Public Housing

Program Services (Not Modeled)

IHWAP provides physical weatherization services rather than cash benefits:

• Air sealing, insulation, HVAC repair/replacement
• Up to $20,000 for energy-related work
• Up to $4,000 for health and safety measures

Not modeled as services depend on home-specific energy audits.

New Reusable Components

This PR also adds:

• smi() function in hhs_smi.py - Reusable function for SMI calculations with any period
• additional_person_threshold parameter - Parameterizes the household size threshold (6) for SMI adjustments

Test Plan

• Unit tests for income eligibility (11 tests)
• Unit tests for categorical eligibility (7 tests)
• Unit tests for overall eligibility (5 tests)
• Integration tests with realistic households (7 tests)
• All 30 tests passing

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 100.00%. Comparing base (849bec6) to head (cbad6cf).
⚠️ Report is 35 commits behind head on main.

Additional details and impacted files

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  Files            1         5    +4     
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+ Hits            19        79   +60     

Flag	Coverage Δ
unittests	100.00% <100.00%> (ø)

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