Model Mississippi Working Disabled Medicaid buy-in pathway

[MaxGhenis]

PolicyEngine currently models working-disabled Medicaid buy-in eligibility only for California and Illinois via is_working_disabled_buy_in_for_medicaid. Mississippi has a Working Disabled Medicaid pathway that is not modeled.

Source:

• Mississippi Division of Medicaid, Working Disabled: https://medicaid.ms.gov/medicaid-coverage/who-qualifies-for-coverage/working-disabled/

Key policy details from Mississippi:

• Disabled person works at least 40 hours per month.
• Disability uses the Social Security definition except SGA is not considered.
• Earnings limit: 250% FPL.
• Unearned income limit: 135% FPL.
• Resource limit: $24,000 individual / $26,000 couple.
• Premium applies above 150% FPL.

Why this matters:

• For SSI asset-limit analyses, we found many marginal SSI recipients in Mississippi who report Medicaid at baseline but fail PE's modeled baseline Medicaid eligibility because they fail standard ABD/SSI-style resource limits.
• This specific Working Disabled pathway did not explain the zero-earnings Mississippi cluster I checked, but it is a concrete missing Medicaid pathway and should be modeled to improve Medicaid baseline reconciliation and downstream health-cost estimates.

Implementation sketch:

• Add Mississippi to is_working_disabled_buy_in_for_medicaid or split state-specific buy-in formulas.
• Add parameters for work threshold, earned/unearned income limits, resource limits, and premium.
• Add tests for disabled workers with resources between $2k and $24k qualifying under this pathway.