The short answer
Your Initial Enrollment Period is a seven-month window: the three months before your 65th-birthday month, your birthday month, and the three months after. But knowing the window isn't the same as knowing what to do and when. This is a simple month-by-month plan so nothing slips.
The single most important tip: to have coverage ready the month you turn 65, act in the three months before your birthday, not after. Waiting until after can delay your start date.
6 to 4 months before 65
Start by deciding your path. Are you retiring and moving straight onto Medicare, or working past 65 with employer coverage? That answer changes everything about your timeline. If you're retiring, this is when to learn how the parts fit and start comparing whether Original Medicare with a supplement or Medicare Advantage suits you.
This is also the time to build your personalized checklist. Our free My Medicare Timeline planner lets you map your own dates and steps so you're not tracking it all in your head.
3 months before to your birthday month
This is the action window. If you're not being automatically enrolled, sign up for Medicare during these three months so your coverage can begin the first day of your birthday month. Choose your Part D drug plan and, if you're going the Original Medicare route, your Medigap supplement — this is when your one-time Medigap open enrollment window opens too.
Getting this done before your birthday month is what guarantees no gap. Our Turning 65 guide walks through the decisions to make in this window.
Your birthday month and the 3 months after
If you didn't enroll earlier, you still can during your birthday month and the three months after — but coverage may start later, potentially leaving a gap. That's why earlier is better. Once you're enrolled, confirm your cards arrive and your doctors and prescriptions are covered under whatever you chose.
After your Initial Enrollment Period, changes happen during the annual windows rather than any time you like, so it pays to get the initial choice right. If you're still working at 65, your timeline is different and driven by when your employer coverage ends instead.
Frequently Asked Questions
When should I sign up for Medicare before turning 65?
In the three months before your birthday month, so coverage can start the first day of your 65th-birthday month with no gap. Your Initial Enrollment Period is the seven months around your birthday.
What happens if I wait until after my birthday to enroll?
You can still enroll in your birthday month and the three months after, but your coverage may start later, which can leave a gap. Enrolling early avoids that.
When does my Medigap window open?
Your one-time six-month Medigap open enrollment window opens when you're 65 or older and enrolled in Part B — so it lines up with enrolling during your Initial Enrollment Period.
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