Medicare enrollment timeline
Used only to work out your dates. Nothing is sent anywhere — this runs in your browser.
This is an estimate for information only, not advice, an offer of coverage, or an eligibility decision.
Seven months, not three
The Initial Enrollment Period runs for the three months before the month you turn 65, that month, and the three months after. Most people think of it as a birthday deadline; it is a window, and where you sign up inside it changes when your coverage starts.
Signing up early starts coverage sooner
Sign up in the three months before the month you turn 65 and Part B starts the month you turn 65. Sign up during that month or later and it starts the month after you sign up. There is no advantage to waiting.
Born on the first? Everything shifts a month
If your birthday falls on the first of a month, Medicare treats you as turning 65 in the previous month. Your enrollment window and your coverage start date both move a month earlier. It is an easy thing to miss and it changes real dates.
Still working at 65
If you have coverage through your own or a spouse’s current employment, you may be able to delay Part B without a penalty and use a Special Enrollment Period later. Whether that applies depends on the size of the employer, so check before relying on it.
Common questions
When can I first sign up for Medicare?
During your Initial Enrollment Period: the three months before the month you turn 65, the month itself, and the three months after. Seven months in total.
What happens if I miss it?
You may pay a Part B late enrollment penalty for as long as you have Part B, and you may have to wait for the General Enrollment Period, January 1 to March 31, with coverage starting the month after you sign up.
My birthday is on the first of the month. Does that matter?
Yes. Medicare counts you as turning 65 in the previous month, so your enrollment window and your coverage start date both move a month earlier.
Can I delay Medicare if I am still working?
Often yes, if you have coverage through current employment. A Special Enrollment Period may let you sign up later without a penalty, but the rules depend on the employer’s size, so confirm before you decide.
Sources and method
- When does Medicare coverage start? — Medicare.gov (CMS)