Medicaid and Children’s Health Insurance Plan (CHIP) programs have played a key role in responding to the COVID-19 pandemic, providing an important safety net for health insurance coverage for millions of people during this unprecedented public health crisis. The Families First Coronavirus Response Act enacted the continuous coverage requirement, which provides a 6.2 percentage point increase in federal matching funds for states that maintain continuous Medicaid enrollment until the end of the public health emergency. Subsequently, administrative records show that enrollment in Medicaid and CHIP has grown substantially.

However, key federal surveys such as the American Community Survey have failed to show the extent of this growth in the population with Medicaid/CHIP coverage. This brief describes our analysis of these estimates, focused on the size of the “Medicaid undercount”, the misalignment between survey estimates of self-reported Medicaid coverage, and enrollment counts obtained from Medicaid/CHIP administrative data.

The Medicaid undercount in the 2021 American Community Survey (ACS) was larger than in earlier years, which we believe was tied, at least in part, to the Medicaid continuous coverage requirement. In the brief, we also present analysis of two years of linked data from the Current Population Survey Annual Social and Economic and Supplement (CPS ASEC). Our results suggest that despite having continuous coverage, many enrollees may not have known they were still covered by Medicaid.

Related Resources

• SHADAC Blog: Understanding the Undercount of Medicaid Enrollees in the 2020 Current Population Survey Health Insurance Coverage Data
• Research Article: Medicaid Expansion and the Medicaid Undercount in the American Community Survey
• Past SHADAC Project: Medicaid Undercount Project