The enrollment window
IEP typically starts 3 months before your 65th birthday month and lasts 7 months total. Signing up earlier in the window can help coverage start when you want it to. Waiting until after the window can create gaps or penalties unless an exception applies.
If you have employer coverage
If you or a spouse is still working at a company with 20 or more employees, you may be able to delay Part B without a late penalty. Get written confirmation that the coverage is creditable. HSA contributions generally must stop once you enroll in Medicare.
Decisions after Parts A and B
Once Original Medicare is in place — or you have chosen Medicare Advantage — you still need a plan for prescriptions and for the remaining medical costs. That is the Advantage vs. Supplement decision, plus Part D.
Common mistakes at 65
Missing IEP, assuming a Marketplace plan can continue unchanged, delaying Part B without a valid reason, forgetting Part D, and choosing a plan because a friend likes it are all avoidable. Your doctors, drugs, and travel habits are the better starting point.