The Reinsurance Institute simulated the effects of reinsurance on individual and employer behavior, observing state-specific characteristics. We constructed a baseline database for each state by reweighting and combining multiple data sources to create a profile of individual-level demographics and health expenditures, allowing for the computation of individual-level premiums. We grouped health insurance units together into risk pools consistent with state market rules to calculate the change a reinsurance subsidy would have on the premium levels faced by individuals and employers. These price changes drove simulated changes in premium and coverage levels, offer and take-up rates, and state costs.