MO MHABD: no SGA screen in the 209(b) SSI-recipient Medicaid pathway

[hua7450]

Summary

Missouri denies Spend Down and Non-Spend Down MHABD coverage to individuals with earnings over the Substantial Gainful Activity (SGA) threshold, but the model's Section 209(b) SSI-recipient pathway (is_209b_ssi_recipient_for_medicaid) applies no SGA screen. A household asserting SSI receipt with wages far above SGA is found Medicaid-eligible under SSI_RECIPIENT.

Reported by an API partner: an SSI recipient with $4,685/month in wages ($56,220/year) returned eligible under SSI_RECIPIENT in Missouri.

Sources

• MO DSS MHABD Manual § 0840.010.35 (Spend Down and Ticket to Work): "If an individual's earnings are over the Substantial and Gainful Activity (SGA) threshold, they are not eligible for Spend Down or Non-Spend Down coverage." https://dssmanuals.mo.gov/mo-healthnet-for-the-aged-blind-and-disabled/0840-000-00/0840-010-00/0840-010-35/
• MO DSS December 1973 Eligibility Requirements Manual, Appendix D (Substantial Gainful Activity): the Medical Review Team "uses Social Security's methodology on SGA for determining disability"; carries SSA's annual amounts (2026: $1,690/month non-blind, $2,830/month blind). https://dssmanuals.mo.gov/december-1973-eligibility-requirements/substantial-gainful-activity/
• 42 CFR 435.121: in a 209(b) state, an SSI recipient qualifies for Medicaid only by meeting the state's own more restrictive aged/blind/disabled criteria — the bridge that makes § 0840.010.35 binding on SSI recipients.

Scope note from the manual's structure: SGA appears only under chapter 1060, "Disability (PTD Eligibility Criteria)". The blind category (AB) is vision-based (ch. 1055) and the aged category (OAA) has no SGA test, so the screen applies to the non-blind disability category only. Appendix D's blind amount is an MRT reference for SSA methodology, not an AB eligibility gate.

Mechanism

1. is_209b_ssi_recipient_for_medicaid gates on ssi > 0 or reported receives_ssi. receives_ssi is a pure input with no formula, and a directly supplied ssi amount bypasses the derivation chain, so asserted receipt is taken at face value with no SGA or disability re-derivation. (With fully derived inputs the pathway is consistent: computed ssi > 0 already implies passing the SGA screen for the non-blind disabled, and the SSI income test zeroes cash benefits near ~$2,020/month earned anyway.)
2. The income test then runs on medicaid_optional_senior_or_disabled_countable_income, which returns $0 for anyone who is not an SSI-eligible individual/spouse. A wage earner over SGA fails is_ssi_disabled (which includes the SGA screen), so is not an SSI-eligible individual, so their countable income is zeroed — and $0 trivially passes Missouri's ~$1,131/month limit. Note this zeroing is load-bearing (the income-eligibility tests sum the variable over the tax unit, and deemed spousal/parental income lands on the eligible member's record), so the fix belongs at the categorical gate, not in the income measure.

Proposed fix

Add an SGA exclusion to is_209b_ssi_recipient_for_medicaid, scoped inline to Missouri (only MO's manual is verified; the other seven 209(b) states are unchecked, and 1634/SSI-criteria states have no legal room for such a gate):

is_excluded_sga_earner = (
    (state == "MO")
    & person("ssi_engaged_in_sga", period)
    & ~person("is_ssi_aged", period)
)

ssi_engaged_in_sga already exempts the blind and reads the non-blind SGA amount from gov/ssa/sga/non_blind.yaml ($1,690/month in 2026); ~is_ssi_aged exempts the aged (OAA).

Known trade-off (document in the PR)

Section 1619(a) (42 U.S.C. 1382h) lets a continuing SSI recipient work above SGA and keep cash benefits until roughly $2,020/month earned, and POMS SI 02302.010 retains Medicaid for 1619(a)/(b) eligibles in 209(b) states given prior-month Medicaid eligibility. The model cannot observe "continuing recipient with prior-month Medicaid", so the gate over-excludes genuine 1619(a) continuers in the roughly $1,690–$2,020/month band. The reported case is unaffected: $56,220/year also exceeds Missouri's 2026 1619(b) threshold of $55,181 (POMS SI 02302.200). Related: #4732 tracks the SSI-side principle that SGA applies only at initial eligibility.

Related issues

• Only apply SGA to SSI upon initial eligibility #4732 (SGA should apply to SSI only at initial eligibility — the 1619(a) tension above)
• Add blind SGA #4062 (blind SGA parameter; deliberately unused here since MO's AB category is vision-based)
• Deduct impairment-related work expenses from SSI countable earned income and SGA #3669 (IRWE not deducted before the SGA comparison; this gate would inherit that simplification via ssi_engaged_in_sga)