$300,000 in taxable home-sale gains can lift a couple’s Medicare premiums from about $406 a month to more than $800 once IRMAA is applied.
Medicare bases premiums on tax returns from two years earlier, so selling a highly appreciated home at 63 or later can trigger higher bills only after retirees enroll.
The surprise is growing as longtime owners in expensive markets sit on hundreds of thousands of dollars in appreciation, sometimes more than $1 million.
Advisers say planning can blunt the hit by selling before 63 when possible, delaying a move, or using the primary-residence capital-gains exclusion of up to $250,000 for individuals and $500,000 for couples.