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: The authors use administrative tax data to measure Medicaid enrollment and income in 2017, they use survey data to measure monthly income, and they use administrative data to identify Medicaid enrollment pathways.

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). The authors also estimate that more than 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.

Conclusions: 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.