You sign up for Medicare mostly through Social Security, and the steps depend on your age and whether you already get Social Security benefits. Here is a simple, U.S.-focused overview.

Check if you get it automatically

If you are already getting Social Security or Railroad Retirement benefits at least four months before you turn 65, you are usually enrolled automatically in Medicare Part A and Part B starting the month you turn 65. About two weeks after enrollment, a Medicare card is mailed to you in a welcome packet.

If you are under 65 and have been on Social Security disability benefits for 24 months, you also generally get Medicare automatically and will receive a card in the mail.

Know when you can sign up

Most people use the “Initial Enrollment Period” when they first become eligible. This is a 7‑month window that starts 3 months before the month you turn 65, includes your birthday month, and ends 3 months after.

If you miss this and do not qualify for a Special Enrollment Period (for example, because you had employer group coverage), you may have to wait for the General Enrollment Period and could pay late penalties.

Ways to sign up

If you are not enrolled automatically, you generally sign up through Social Security (or the Railroad Retirement Board if you or a spouse worked for the railroad). You can usually enroll in Original Medicare (Part A and Part B) in one of these ways:

• Online: Create or log in to your secure “my Social Security” account and choose the Medicare application.

• By phone: Call Social Security at 1‑800‑772‑1213 (TTY 1‑800‑325‑0778), or the Railroad Retirement Board at 1‑877‑772‑5772 if that applies.

• In person: Make an appointment at your local Social Security office and complete the Medicare application there.

Basic information and documents

To apply, you’ll give personal details like name, address, phone number, and your Social Security number. You may also need proof of age and status, such as a birth certificate, U.S. citizenship or lawful residency documents, and recent W‑2 or self‑employment tax info if requested.

After you submit the application, you receive a confirmation and then a Medicare card in the mail, typically within a few weeks.

Key pieces at a glance

What you do| Where/How you do it| When it usually applies
---|---|---
Let automatic enrollment happen| No action; card mailed to you| Already on Social Security/RRB at 65 or disabled 17
Apply for Part A and/or Part B| Online, phone, or Social Security office| Not yet on Social Security or not auto‑enrolled 13
Use your Initial Enrollment Period| 7‑month window around 65th birthday| Most people new to Medicare at 65 78
Use a Special Enrollment Period| Through Social Security/RRB| Qualifying events like losing employer coverage 710

If you share your age, whether you already get Social Security, and if you’re still working with employer coverage, more tailored step‑by‑step guidance can be outlined.