For most people, yes — and the window is only seven months wide. Here is who can safely wait, and who cannot.
Key takeaways
- Your Initial Enrollment Period is seven months: the three months before you turn 65, your birthday month, and the three months after.
- If you have not started Social Security nothing is automatic, and only coverage from current employment lets you delay Part B safely.
- Act in the three months before your 65th birthday, or if working past 65, get CMS-L564 signed by HR before you leave.
What is your 7-month window?
Your Initial Enrollment Period runs seven months: the three months before the month you turn 65, your birthday month, and the three months after.1
Who is enrolled automatically?
If you are already receiving Social Security when you turn 65, you are enrolled in Part A and Part B automatically.1 Your card arrives in the mail. You do not have to do anything — though you can decline Part B if you have employer coverage. Residents of Puerto Rico are the exception: Part A is automatic, but you must sign up for Part B yourself.1
From Next Chapter TodayThree things that matter, every weekday morning.The free newsletter from Next Chapter Today. No panic. No politics. Just clarity.Subscribe free →Who must sign up themselves?
If you have not started Social Security, nothing is automatic. Nobody calls. No card arrives. You have to enroll yourself at ssa.gov or by calling 1-800-772-1213.5
Who can safely delay?
If you are still working and have group health coverage through current employment — yours or your spouse's — you can generally delay Part B without penalty, then use a Special Enrollment Period when that coverage ends.4
What does the penalty cost?
Miss your window without qualifying coverage and the Part B late enrollment penalty is 10% for each full 12-month period you could have had Part B and didn't. It is added to your premium for as long as you have Medicare. It is not a one-time fee.2
Part D has its own penalty: 1% of the national base premium — $38.99 in 2026 — for every month you went without creditable drug coverage. Also permanent.2
And if you miss the window entirely, you may have to wait for the General Enrollment Period, January 1 through March 31, to sign up at all.
What should you do next?
- Mark the three months before your 65th birthday — that is when to act.
- If you are working past 65, confirm in writing that your coverage is based on current employment.
- If it is not, enroll during your Initial Enrollment Period.
- Ask your employer's HR to sign CMS-L564 before you leave, so a Special Enrollment Period is documented.
Sources
- medicare.gov — Medicare & You 2026 (PDF)
- medicare.gov — Avoid late enrollment penalties
- medicare.gov — When does Medicare coverage start
- medicare.gov — Working past 65
- medicare.gov — Ready to sign up for Part A and Part B
Do I Have to Sign Up for Medicare at 65?
The full guide: the windows, the exceptions, and the paperwork that proves you qualify.
The Social Security PlaybookWhen to claim, how to protect a spouse, and the 75 questions people actually ask. By Kwame Kuadey.About the book →Next Chapter Today is not a government website and is not affiliated with the Social Security Administration or any agency. This article is educational and is not individualized legal, medical, tax or financial advice. Confirm your own figures with the agency before you act.
