In government-sponsored health insurance, subsidy design affects market outcomes. First, holding premiums fixed, subsidies determine insurance uptake and average cost. Insurers then respond to these changes, adjusting premiums. Combining data from the first four years of the California ACA...

We study age-rating restrictions in the health insurance marketplaces introduced by the Affordable Care Act. Because most buyers are subsidized, although age-rating restrictions affect pre-subsidy premiums, participation is primarily driven by subsidy generosity rather than pricing decisions....

Under the Affordable Care Act, individual states have discretion in how they define coverage regions, within which insurers must charge the same premium to buyers of the same age, family structure, and smoking status. We exploit variation in these definitions to investigate whether the size of...

To design premium subsidies in a health insurance market it is necessary to estimate consumer demand, cost, and study how different subsidy schemes affect insurers' incentives. I combine data on household-level enrollment and plan-level claims from the Californian Affordable Care Act insurance...

We study how the politicization of policies designed to correct market failures can undermine their effectiveness. The Patient Protection and Affordable Care Act (ACA) was among the most politically divisive expansions of the US government. We examine whether partisanship distorted enrollment...