Turning 65 comes with a to-do list nobody hands you, and a few deadlines that don't forgive. Here it is in order, so nothing sneaks up.
Your enrollment windows, on one line.
Months before and after the month you turn 65.
Your timeline, month by month
- 12 months before
Work out whether you'll still be working
This changes everything else. If you'll have employer coverage from a company with 20+ employees, you may be able to delay Part B without penalty. If not — or if the employer is smaller — you'll want to enroll on time. Getting this wrong is the most expensive mistake on this page.
- 6 months before
Plan your last HSA contribution
You can't contribute to a Health Savings Account for any month you're enrolled in Medicare. Enrolling at 65, that means your contributions stop the month Medicare begins, and this year's limit is prorated. Working past 65 and enrolling later? Part A is backdated up to six months (never earlier than the month you turned 65), so stop contributing six months before you apply. Getting this wrong creates a tax problem, so it deserves a note on the calendar.
- 4 months before
Take stock of your doctors and prescriptions
Write down every doctor you'd be unhappy to lose and every medication with its dose. This one list drives most of the decisions that follow — whether a network works for you, and which drug plan actually covers what you take.
- 3 months before — your window opens
Initial Enrollment Period begins
Your IEP runs seven months: the three months before your birthday month, that month, and the three after. Enrolling in the first three generally means coverage starts on the first day of your birthday month, with no gap.
- 2–3 months before
Decide the big one: Supplement or Advantage
This is the fork in the road. A Supplement means any doctor who accepts Medicare, predictable costs, and a higher premium. An Advantage plan means a low or $0 premium, extra benefits, and a network. Neither is universally right — but when you decide matters: see the Medigap window below.
- 1 month before
Sort your Part D drug plan
If you go the Supplement route, prescriptions are a separate plan — and the right one depends entirely on your medication list. Even with no current prescriptions, enrolling in something avoids a late penalty that lasts for life.
- Your birthday month
Coverage begins — check your card and your pharmacy
Confirm your card arrived, your plan shows active, and your pharmacy has your new information on file. A ten-minute check now prevents a bad surprise at the counter.
- Your birthday month, once Part B starts
Your Medigap Open Enrollment window starts — six months
This is the one to circle. For six months you can buy any Medicare Supplement sold in your state with no health questions at all. No carrier can decline you or charge you more for your history. Once it closes, in most states they can do both.
- 3 months after
Your IEP closes
After this, changes generally wait for Annual Enrollment in the fall — unless a life event opens a Special Enrollment Period.
- Every October thereafter
Review, don't autopilot
Annual Enrollment runs October 15 to December 7. Plans change their formularies, networks and costs every single year. The plan that fit you last year may not this year, and reviewing costs nothing.
If you remember one thing from this page
The Medigap Open Enrollment window — six months from when you're 65 and on Part B — is the only guaranteed chance to buy a Supplement with no health questions. People who start on an Advantage plan and try to switch to a Supplement two years later often find they no longer qualify. If there's any chance you'll want a Supplement, that window is when to act.
The Medicare year, at a glance.
The two windows that come round every year, and when we talk.
Common mistakes I see
- Assuming you'll be enrolled automatically. Only people already drawing Social Security are. Everyone else has to sign up.
- Skipping Part D because you take nothing. The late penalty is permanent, and health changes.
- Choosing on premium alone. The cheapest plan in January can be the expensive one by December, depending on how you actually use care.
- Waiting until the last month. Everything above is easier with time, and some of it can't be undone.