Using Discontinuous Eligibility Rules to Identify the Effects of the Federal Medicaid Expansions on Low-Income Children

Despite intensive scrutiny, the effects of Medicaid expansions on the health insurance status of low-income children remain controversial. We reexamine the effects of the two largest federally mandated expansions which offered Medicaid coverage to low-income children in specific age ranges and birth cohorts. We use a regression discontinuity approach, comparing Medicaid enrollment, private insurance coverage, and overall insurance coverage on either side of the age limits of the laws. We conclude that the modest impacts of the expansions on health insurance coverage arose because of very low takeup rates of the newly available coverage, rather than from crowdout of private insurance coverage. © 2004 President and Fellows of Harvard College and the Massachusetts Institute of Technology.