Medicare Enrollment Window Checker
Your Initial Enrollment Period is the seven-month window around your 65th birthday: the three months before your birthday month, your birthday month, and the three months after (Medicare.gov). Enter your date of birth and see your exact dates — including the six-month Medigap window that only opens once.
An educational estimate of your windows, not an official determination — Medicare and Social Security set your actual dates, and a Special Enrollment Period can replace them entirely. Nothing you enter is stored; the calculation runs entirely in your browser.
Frequently asked questions
When can I sign up for Medicare?
Your Initial Enrollment Period is the seven months around your 65th birthday — the three months before your birthday month, your birthday month, and the three months after (Medicare.gov). Enrolling in the three months before is what gets your coverage started the month you turn 65.
What happens if my birthday is on the first of the month?
Medicare treats your eligibility as starting the month before, which shifts your whole seven-month window one month earlier. The checker handles this automatically — it is the single most commonly missed detail in Medicare timing.
What is the Medigap open-enrollment window?
The six months beginning the month your Part B takes effect. During those six months a Medicare Supplement carrier must sell you any plan it offers at its best available rate regardless of health history. After it closes, most carriers can medically underwrite you and decline.
I'm still working at 65 — do these dates apply to me?
Possibly not. Creditable group coverage from an employer with 20 or more employees generally lets you delay Part B penalty-free and use a Special Enrollment Period when that coverage ends. COBRA and retiree coverage usually do not count, which is where expensive mistakes happen.
Method: seven-month Initial Enrollment Period and the birthday-on-the-first shift per Medicare.gov; six-month Medigap open enrollment measured from your Part B effective date; Annual Enrollment Period October 15 – December 7 every year. If you are working past 65 with employer coverage a Special Enrollment Period may replace these dates — read the full guide or have us confirm your dates.
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More calculators on the free tools hub, or read the background in Medicare 101.