Signing up for Medicare Part A (Hospital Insurance) is usually done through the Social Security Administration (SSA), either online, by phone, or in person at a local office.

Who Gets Part A Automatically?

Most people don’t have to actively “sign up” for Part A if they’re already getting Social Security or Railroad Retirement Board (RRB) benefits.

  • If you’re turning 65 and already receive Social Security retirement or disability benefits, you’ll be automatically enrolled in both Part A and Part B about 3 months before your 65th birthday.
  • If you’re under 65 but have been getting Social Security Disability Insurance (SSDI) for 24 months, you’ll also be automatically enrolled in Part A and Part B.

In these cases, you’ll get a Medicare card in the mail about 3 months before your coverage starts.

When You Need to Actively Sign Up

You’ll need to manually apply for Part A if:

  • You’re turning 65 but not yet getting Social Security or RRB benefits.
  • You’re under 65, disabled, and haven’t been on SSDI for 24 months yet.
  • You’re eligible for premium‑free Part A (because you or your spouse paid Medicare taxes for at least 10 years) but want to enroll outside of the automatic enrollment window.

If you delay enrollment and don’t qualify for premium‑free Part A, you may have to pay a monthly premium for Part A later.

How to Sign Up for Part A

There are three main ways to apply for Medicare Part A:

1. Online (Easiest & Fastest)

  • Go to the official Social Security website: www.ssa.gov.
  • Create or log in to your my Social Security account.
  • Look for the option to “Sign up for Medicare” or “Apply for Medicare benefits”.
  • You’ll fill out basic info (name, SSN, date of birth, address, etc.) and choose whether you want Part A only, Part B only, or both.
  • After submitting, you’ll get a welcome package and your Medicare card in the mail in about 2 weeks.

2. By Phone

  • Call Social Security at 1‑800‑772‑1213 (TTY 1‑800‑325‑0778).
  • Ask to apply for Medicare Part A (and Part B, if desired).
  • A representative will help you complete the application over the phone.

3. In Person

  • Visit your local Social Security office.
  • Bring:
    • Your Social Security card (or number)
    • Proof of age (birth certificate, passport, etc.)
    • Proof of U.S. citizenship or lawful residency, if needed.
  • A claims representative will help you fill out the application.

If you or your spouse worked for a railroad, contact the Railroad Retirement Board at 1‑877‑772‑5772 instead.

What You’ll Need to Apply

To sign up for Part A, have ready:

  • Your Social Security number (or Railroad Retirement number).
  • Your date and place of birth.
  • Your mailing address and phone number.
  • If applicable, your spouse’s work history (to check if you qualify for premium‑free Part A).
  • Proof of U.S. citizenship or lawful permanent residence (if not already in SSA records).

When to Sign Up (Timing Matters)

Medicare has enrollment periods that affect when coverage starts and whether you face late‑enrollment penalties.

Initial Enrollment Period (IEP)

This is your main window to sign up when you first become eligible:

  • Starts 3 months before the month you turn 65
  • Includes the month you turn 65
  • Ends 3 months after the month you turn 65.

If you sign up during this 7‑month window, your Part A coverage usually starts the month you turn 65 (or earlier, if you’re already eligible).

Special Enrollment Period (SEP)

If you’re still working and covered by a group health plan (through your or your spouse’s current job), you may qualify for a Special Enrollment Period.

  • You can delay Part B without a penalty, but you can still sign up for Part A (often premium‑free) while still working.
  • You generally have 8 months after your group coverage ends (or your employment ends, whichever comes first) to enroll in Part B without a penalty.

Premium‑Free vs. Paid Part A

  • Most people get premium‑free Part A if they (or their spouse) paid Medicare taxes while working for at least 10 years (40 quarters).
  • If you don’t meet the work requirement, you can still buy Part A, but you’ll pay a monthly premium (the amount changes each year).

After You Sign Up

  • About 2 weeks after applying, Social Security will mail a welcome package with your Medicare card.
  • Your Part A coverage start date depends on when you applied and your eligibility (for example, if you applied during your IEP, it usually starts the month you turn 65).
  • Once you have Part A, you can also decide whether to enroll in Part B (Medical Insurance), Part D (prescription drug coverage), and/or a Medicare Advantage (Part C) plan.

Helpful Resources

  • Medicare.gov “How do I sign up for Medicare?” tool – Answers a few questions about your situation and tells you exactly how to enroll.
  • Social Security’s Medicare page – Explains eligibility, enrollment periods, and how to apply online.
  • CMS Application for Medicare Part A (Form CMS‑18F5) – The official paper application if you prefer to mail or hand in a form.

If you’re unsure about your work history, current coverage, or when to enroll, it’s a good idea to call Social Security or talk with a State Health Insurance Assistance Program (SHIP) counselor in your state for free, unbiased help.

Bottom line:
If you’re already getting Social Security, you’ll usually be signed up for Part A automatically. If not, you can sign up online at SSA.gov, by phone, or in person during your Initial Enrollment Period (around age 65) to avoid delays or penalties.