Why Some Nonelderly Adult Medicaid Enrollees Appear Ineligible Based on Their Annual Income.

Context: Recent studies have highlighted Medicaid enrollment among middle- and higher-income populations and questioned whether the program is reaching those for whom it is intended.

Methods: Medicaid enrollment and income in 2017 are measured using administrative tax data, monthly income is measured using survey data, and Medicaid enrollment pathways are identified in administrative data.

Findings: Among 38.8 million nonelderly adults in Medicaid at any point in 2017, 24.4 million had annual income below their state's typical eligibility threshold, and 14.4 million (37%) had income above the threshold. Among those above the threshold, 3.5 million enrolled through a pathway allowing higher income (pregnant women, the "medically needy", and others); we also estimate that over 12 million had at least one month with income below the threshold and roughly 4 million had at least five months with income below the eligibility threshold.

Conclusion: Pathways allowing higher income account for one-quarter of enrollees with annual incomes above typical thresholds. Among low-income adults, month-to-month variation in income is common and can account for most or all of the remaining enrollees with annual incomes above typical thresholds. A complete accounting of eligibility status would require merged data on income, Medicaid enrollment, and family structure.