HUD adjusted income is pre-HOTMA: deduction amounts, 10% medical threshold, dependent definition, and missing disability assistance deduction (24 CFR 5.611)

## Background

HUD's HOTMA final rule (88 FR 9600, effective **2024-01-01**; universal mandatory PHA compliance **2025-07-01** per Notice PIH 2024-38) amended 24 CFR 5.611 adjusted income. The model's income side (24 CFR 5.609 source lists, dated 2024-01-01) is HOTMA-aligned, but `hud_adjusted_income` still applies pre-HOTMA rules, so 2024+ simulations mix post-HOTMA income definitions with pre-HOTMA deductions.

Verified against [24 CFR 5.611](https://www.law.cornell.edu/cfr/text/24/5.611), [24 CFR 5.603](https://www.law.cornell.edu/cfr/text/24/5.603), and the [HUD CY2026 inflationary adjustments](https://www.huduser.gov/portal/sites/default/files/datasets/inflationary-adjustments/CY2026-Revised-Amounts-And-Passbook-Rate.pdf) (2026-07-06):

## Gaps

1. **Elderly/disabled deduction is $400** (2001 value). § 5.611(a)(2): $525 effective 2024, CPI-W-indexed rounded down to a $25 multiple → $525 in 2025, **$550 in 2026**.
2. **Medical expense threshold is 3%**. § 5.611: combined unreimbursed health/medical + attendant care expenses are deductible only above **10% of annual income** (transitional 5%/7.5% phased hardship relief is individual-circumstance and reasonable to leave unmodeled).
3. **Dependent deduction counts children only** (`is_child`). § 5.603 dependent = family member (excluding foster members) other than head or spouse who is **under 18, disabled, or a full-time student**. The existing `is_hud_dependent` variable already implements this. Amount: $480 through 2025, **$500 in 2026**.
4. **Disability assistance deduction not implemented** (`# TODO: Attendant care` in `hud_adjusted_income.py`). § 5.611 deducts unreimbursed reasonable attendant care and auxiliary apparatus expenses (combined with medical under the single 10% threshold post-HOTMA), capped at the earned income of the 18+ members enabled to work.

## Effect

For elderly/disabled families with medical expenses, adjusted income (and thus TTP) is misstated: the too-small flat deductions push the voucher down, while the too-low 3% threshold pushes it up. Families with disabled-adult or adult-student dependents miss the dependent deduction entirely.

## Dating decision

Parameters should use dated entries at **2024-01-01** (regulatory effective date, matching the already-shipped § 5.609 income side), with a comment noting 2025-07-01 as the universal mandatory PHA compliance date. Pre-2024 years keep $400/$480/3%.

## Related

- #1053, #5164 (HUD income definition — the § 5.609 source-list portion has landed)
- Note: workers' compensation is deliberately **not** counted, per post-HOTMA § 5.609(b)(5) (insurance payments for personal losses, including workers' comp) — not a gap.

Start in hud_adjusted_income.py, inspect the existing is_hud_dependent logic and the TODO for attendant care, then compare the current deductions with 24 CFR 5.611 and 5.603. Done means dated 2024-01-01 parameters apply HOTMA deductions while pre-2024 values remain unchanged, including the disability assistance deduction and single 10% threshold.

Written by the indexing model from the issue text.