You sign up for Medicare either automatically through Social Security or by actively enrolling, usually during a 7‑month window around your 65th birthday. For most people, the actual sign‑up happens through Social Security, not directly at Medicare.

Basic sign‑up rules

  • Most people can first enroll during the Initial Enrollment Period , which starts 3 months before the month you turn 65, includes your birthday month, and ends 3 months after (7 months total). Missing this window can lead to late penalties for Part B and Part D in many cases.
  • If you are already getting Social Security or Railroad Retirement benefits at least 4 months before you turn 65, you are usually enrolled in Medicare Part A automatically and often Part B as well, and a red‑white‑and‑blue card is mailed to you.

Ways to sign up

If you are not automatically enrolled, you generally enroll through Social Security.

  • Online:
    • Go to the Social Security website and choose the option to sign up for Medicare or “Medicare only.” You either log in to or create a my Social Security account, then complete the online application.
  • By phone:
    • Call Social Security at 1‑800‑772‑1213 (TTY 1‑800‑325‑0778) to apply or ask questions.
  • In person:
    • Contact or visit your local Social Security office; in some cases, if you or your spouse worked for a railroad, you enroll through the Railroad Retirement Board instead.

What you’re actually enrolling in

Medicare sign‑up usually happens in stages, even though people often call it all just “Medicare.”

  • Original Medicare
    • Part A: Hospital insurance; often premium‑free if you or a spouse worked and paid Medicare taxes long enough.
* Part B: Medical insurance (doctor visits, outpatient care); has a monthly premium and possible late‑enrollment penalties if you delay without other qualifying coverage.
  • After Parts A & B
    • You can choose either a Medicare Advantage plan (Part C) or stay with Original Medicare and possibly add a Part D drug plan and/or a Medigap (supplement) policy. These are usually purchased from private insurers after you have your Medicare number.

Timing and special situations

Enrollment timing matters a lot for costs and penalties.

  • If you keep working past 65 and have employer coverage, you may be able to delay Part B (and sometimes Part D) without penalty, then use a Special Enrollment Period when that coverage ends.
  • If you miss both your Initial Enrollment Period and any Special Enrollment Period you qualify for, you might have to wait for a General Enrollment Period and pay higher premiums for late enrollment.

Simple step‑by‑step starting point

For someone turning 65 who is not yet on Social Security:

  1. Mark your Initial Enrollment Period (3 months before to 3 months after the month you turn 65).
  1. Decide whether you want just Part A or both Part A and Part B, based on your current job and health insurance.
  1. Go to the Social Security site during that window and submit an online “Sign up for Medicare” application (or call or visit their office).
  1. After you get your Medicare card, use your Medicare number to shop for a drug plan, Medicare Advantage plan, or Medigap if you want extra coverage.

Information gathered from public forums or data available on the internet and portrayed here.