Working Paper: NBER ID: w22213
Authors: Molly Frean; Jonathan Gruber; Benjamin D. Sommers
Abstract: Using premium subsidies for private coverage, an individual mandate, and Medicaid expansion, the Affordable Care Act (ACA) has increased insurance coverage. We provide the first comprehensive assessment of these provisions’ effects, using the 2012-2015 American Community Survey and a triple-difference estimation strategy that exploits variation by income, geography, and time. Overall, our model explains 60% of the coverage gains in 2014-2015. We find that coverage was moderately responsive to price subsidies, with larger gains in state-based insurance exchanges than the federal exchange. The individual mandate’s exemptions and penalties had little impact on coverage rates. The law increased Medicaid among individuals gaining eligibility under the ACA and among previously-eligible populations (“woodwork effect”) even in non-expansion states, with essentially no crowd-out of private insurance. Overall, exchange premium subsidies produced 40% of the coverage gains explained by our ACA policy measures, and Medicaid the other 60%, of which 1/2 occurred among previously-eligible individuals.
Keywords: Affordable Care Act; health insurance coverage; Medicaid expansion; premium subsidies
JEL Codes: H21; I13
Edges that are evidenced by causal inference methods are in orange, and the rest are in light blue.
| Cause | Effect |
|---|---|
| ACA (G52) | insurance coverage (G52) |
| price subsidies (H20) | uninsured rate (I13) |
| Medicaid expansion (I18) | coverage among newly eligible individuals (G52) |
| woodwork effect (L73) | coverage impact (G52) |
| individual mandate penalties (H26) | coverage rates (G52) |
| ACA (G52) | private insurance crowdout (I13) |