Missouri MHABD: SGA screen on the 209(b) pathway and individual/couple income standard

[hua7450]

Summary

Two Missouri MHABD fixes raised by MyFriendBen, plus regression tests for the MHDC parental-deeming behavior they questioned.

Fixes #9316

1. SGA screen on the 209(b) SSI-recipient pathway

Missouri denies spend-down and non-spend-down MHABD coverage when earnings exceed the substantial gainful activity threshold (DSS MHABD Manual § 0840.010.35). is_209b_ssi_recipient_for_medicaid accepts reported SSI receipt at face value, so an asserted recipient with $4,685/month in wages was found eligible under SSI_RECIPIENT.

• New gov/hhs/medicaid/eligibility/categories/ssi_recipient/section_209b/applies_sga_screen.yaml, state breakdown, Missouri true, every other state false (only Missouri's manual is verified).
• The gate is applies_sga_screen & ssi_engaged_in_sga & ~is_ssi_aged. The screen sits under Missouri's permanent-and-total-disability chapter, so the blind (already exempt inside ssi_engaged_in_sga) and the aged are not screened.
• Known trade-off, documented in the formula: section 1619(a) continuing recipients working above SGA cannot be distinguished from new applicants and are over-excluded.

2. Income standard uses the individual or couple guideline, not the tax unit's

Appendix J publishes MHABD standards for an individual and for a couple ($1,131 / $1,533 aged or disabled, $1,330 / $1,804 blind in 2026). medicaid_optional_senior_or_disabled_income_limit computed Missouri's limit from tax_unit_fpg, so a disabled child in a family of four was tested against 85% of the four-person guideline ($2,338/month) instead of $1,131. Missouri now uses the one-person guideline, or the couple guideline for a head or spouse of a joint unit. Units of one or two people are unchanged.

Existing Missouri tests that injected tax_unit_fpg: 15_000 / 20_000 are recomputed from the real 2025 guidelines ($15,650 one person, $21,150 couple). One 209(b) spenddown case has its medical expenses raised so it still lands inside the 2026 individual standard.

3. MHDC parental deeming: tests only

MyFriendBen reported that stepparent and two-disabled-child households returned the children ineligible. Reproduced locally: with meets_ssi_disability_criteria set on the child, the model already deems only from adults flagged as parents (so a stepparent is not a deeming source, matching DSS MHABD Manual § 0805.020.15) and splits deemed income equally between applying disabled children. The reported ineligibility comes from sending is_disabled alone, which no longer feeds SSI disability. Two Missouri cases lock in the stepparent exclusion and the equal split with hand-computed amounts.

Test plan

• CI passes (is_209b_ssi_recipient_for_medicaid, is_209b_ssi_recipient_income_eligible_for_medicaid, medicaid_optional_senior_or_disabled_income_limit, is_optional_senior_or_disabled_income_eligible, parental deeming)
• Household API partner tests unchanged

🤖 Generated with Claude Code

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 100.00%. Comparing base (837a1ad) to head (3bb61a1).
⚠️ Report is 24 commits behind head on main.

Additional details and impacted files

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  Coverage   100.00%   100.00%           
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  Files            3         2    -1     
  Lines           46        44    -2     
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- Hits            46        44    -2     

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unittests	100.00% <100.00%> (ø)

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