Aging Out of Dependent Coverage and Health Insurance Trends, 2014-2019.

Objective: To examine changes in health insurance coverage when adults age out of dependent coverage at age 26 after the implementation of most Affordable Care Act (ACA) provisions. Our analysis also documented differences by sex, race and ethnicity, and state Medicaid expansion status.

Methods: We used a regression discontinuity design and the 2014-2019 American Community Survey to estimate coverage changes (uninsured, any private, employer-sponsored coverage, direct purchase, and Medicaid) at age 26. Our main sample consisted of adult citizens aged 22-29 years.

Results: Uninsurance increased by 2.7% points [95% CI; 1.8-3.4] at age 26, which was driven by a significant decline in any private insurance (3.7% point decrease). Young adults experienced a smaller increase in the uninsured rate on turning age 26 in states that expanded in 2014 compared to nonexpansion states (2.2% and 3.2% point increases, respectively), but the difference was not significant (P = .07). Changes in the uninsured rate at age 26 did not differ significantly by sex or race and ethnicity.

Conclusions: The 2010 dependent coverage provision led to more coverage options among young adults and in turn the uninsured rate declined among a population historically among the most likely to lack coverage. The 2014 Medicaid and Marketplace expansions reduced the uninsured rate even further among young adults. Despite important progress, our findings for 2014-2019 were similar to previous studies using pre-ACA data suggesting that coverage loss remains a risk when adults age out of dependent coverage at age 26.