Does the Individual Mandate Affect Insurance Coverage? Evidence from Tax Returns

We estimate the effect of the ACA's individual mandate on insurance coverage using regression discontinuity and regression kink designs with tax return data. We have four key results. First, the actual penalty paid per uninsured month is less than half the statutory amount. Second, nonetheless, we find visually clear and statistically significant responses to both extensive margin exposure to the mandate and to marginal increases in the mandate penalty. Third, we find substantial heterogeneity in who responds; men are especially responsive. Fourth, our estimates imply fairly small quantitative responses to the individual mandate, especially in the Health Insurance Exchanges.