Rebates on the Ballot: Exposure to the $500 ACA Checks and Voting Behavior in the 2026 Midterm Elections

How do targeted, one-time fiscal rebates distributed amidst a sharp contraction in social insurance generosity affect electoral participation and partisan vote shares? In 2026, the expiration of enhanced Affordable Care Act (ACA) premium tax credits restored the statutory 400% Federal Poverty Level (FPL) subsidy cliff, eliminated zero-dollar ($0) premium plans for millions of households, and raised required premium contributions across all subsidized income tiers. Ahead of the November 2026 midterm elections, the federal executive distributed $500 rebate checks to unsubsidized Marketplace enrollees in the 30 states using the federally facilitated exchange platform. Combining county-level Marketplace enrollment and plan-pricing records with household survey microdata, regional economic indicators, and county-by-contest election returns, I estimate the electoral impact of county exposure to the $500 checks. To address the endogeneity of unsubsidized enrollment, I construct simulated instrumental variables isolating exogenous variation in statutory tax-schedule changes, zero-premium plan termination, and leave-own-rating-area-out insurer pricing applied to a fixed national reference population. Two-stage least squares estimates, supported by leave-one-county-out jackknife, omitted variable bias, and randomization inference checks, demonstrate that check exposure substantially increased voter turnout and Republican two-party vote shares, with the largest effects concentrated in lower-income counties and districts with high minority electorate shares.