Overlapping Eligibility and Enrollment: Human Services and Health Programs Under the Affordable Care Act. Determination of Medicaid eligibility under the ACA


The TRIM3 model is used to simulate Medicaid and CHIP eligibility assuming that the ACA has been fully implemented, and that all states have expanded Medicaid eligibility to 138 percent of poverty. Eligibility is assessed on a month-by-month basis.

Eligibility is simulated as follows:

  1. Adults qualify for Medicaid if they have MAGI at or below 138 percent of the poverty guidelines, or if they have mandatory coverage as SSI recipients.41 Other pathways are assumed to no longer be available. The simulation assumes no continuous coverage for adults.
  2. Children ages 0-18, inclusive, qualify for Medicaid if they have MAGI at or below 138 percent of the poverty guidelines. States that currently (2010) apply continuous enrollment to children were assumed to apply continuous enrollment to children newly-eligible under the ACA.
  3. Children above 138 percent of FPL qualify for Medicaid and CHIP if they qualify under their state’s pre-ACA rules. The modeling of eligibility for CHIP, including for separate state programs, does not exclude from eligibility children who are reported in the survey as covered by employer-sponsored insurance (ESI). Although by federal statute receipt of ESI is incompatible with eligibility for separate CHIP programs,42 children in many states can move from ESI into CHIP.43 Except for our EITC results (as shown in Figure 4),44 using a different assumption would cause only minor changes to the results we report in the body of the paper.

More details are provided below on the assumptions regarding pre-ACA pathways and the modeling of continuous coverage.

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