Last reviewed: September 2026
Want a shorter overview first? See our Turning 65 page. También está disponible en español.
Your Initial Enrollment Period
Your Initial Enrollment Period (IEP) is 7 months long: the 3 months before the month you turn 65, your birthday month, and the 3 months after.
When coverage starts
If you sign up before your birthday month, your coverage generally starts the first day of your birthday month. If you sign up during your birthday month or in the 3 months after, coverage starts the first day of the month after you sign up.
How you’re enrolled
If you already get Social Security retirement benefits — and you’ve been receiving them for at least 4 months before turning 65 — you’re usually enrolled in Parts A and B automatically, and your Medicare card arrives in the mail before your birthday. Otherwise, you sign up through Social Security: online at ssa.gov, by phone, or at a local office.
What Part A and Part B cost
Most people don’t pay a monthly premium for Part A, because they or a spouse paid Medicare taxes for long enough — generally 10 years, or 40 quarters. Part B has a monthly premium set each year, and people with higher incomes pay more. Read more about IRMAA.
Penalties for enrolling late
If you don’t sign up for Part B when you’re first eligible, and you don’t qualify for a Special Enrollment Period through current employment, a late enrollment penalty of 10% is added for each full 12-month period you could have had Part B but didn’t — for as long as you have Part B.
Part D works similarly: if you go 63 or more days in a row without Part D or other creditable drug coverage after your Initial Enrollment Period ends, a penalty may be added to your Part D premium for as long as you have it.
Timing affects your Medigap window
Your Medicare Supplement (Medigap) Open Enrollment Period starts the day your Part B coverage starts, so when you enroll in Part B affects this window too. Learn more about Medicare Supplement.
Your checklist
| When | What to do |
|---|---|
| About 6 months before | Review your current coverage and employer situation. List your doctors and prescriptions. Learn about the two main paths — Medigap vs. Medicare Advantage. |
| About 3 months before (your Initial Enrollment Period opens) | Enroll in Parts A and B, unless you’re delaying Part B with employer coverage — see Working past 65. Choose Medigap + Part D, or a Medicare Advantage plan. |
| Your birthday month | Coverage begins if you enrolled early. Keep your Medicare card and plan documents together. |
| Every fall | Review your coverage during the Annual Enrollment Period. |
How I can help
Turning 65 brings a lot of decisions at once. I’ll walk through your timeline and your options, so you can enroll with confidence. Schedule a review whenever you’re ready.
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