The Treasury Department has begun sending one-time $500 refund checks to more than 950,000 Affordable Care Act enrollees in the 30 states using HealthCare.gov. The payments, funded through unspent insurer user fees, go to policyholders who did not receive federal premium subsidies, most of whom earn more than $62,600 individually or $128,600 for a family of four. Each recipient is also receiving a letter from President Donald Trump claiming the Biden administration overcharged policyholders, a characterization some experts dispute. The refunds arrive as enhanced ACA subsidies have expired, premiums and out-of-pocket costs are rising, and Republicans seek to retain control of Congress in the midterm elections. Trump has separately proposed $5,000 payments to all adult Americans if Republicans retain control, a plan whose prospects remain uncertain.