Should I switch to Medicare at 65 or stay on my employer's health plan?

It depends mainly on your employer's size and the coverage's cost. If you work for a company with 20 or more employees, you can usually delay Medicare without penalty and keep employer coverage as primary. With fewer than 20 employees, Medicare typically becomes primary, so you generally need to enroll at 65 to avoid coverage gaps. Compare total costs: employer premiums versus Medicare Part B (around $185/month base in 2025, more at higher incomes), plus a supplement or Advantage plan. One critical rule — if you're contributing to an HSA, you must stop HSA contributions before enrolling in any part of Medicare, since Medicare and HSA contributions can't coexist. Also watch the eight-month special enrollment window after employment ends to avoid lifelong Part B late penalties. If your employer plan is generous and cheap, staying can make sense; otherwise Medicare often wins.