When and how to register for Medicare Part A

You register for Medicare Part A (hospital insurance) through Social Security, not through Medicare directly. Most people register during a seven-month window that starts three months before the month they turn 65. If you were born on May 15, the window opens February 1 and closes August 31. You can register online at ssa.gov, by phone at 1-800-772-1213, or in person at your local Social Security office.

If you are already receiving Social Security retirement or disability benefits, you are registered automatically. Medicare Part A starts the first day of the month you turn 65, or the first day of the month after you register, whichever is later. If you miss the initial window, you can still register later, but you may face a permanent penalty on your premiums if you wait more than three years.

You will need your Social Security number, birth certificate, proof of citizenship or legal residency, and a photo ID. If you are registering by phone or online, have these documents nearby but you do not need to mail them in unless Social Security asks you to verify something later.

Key Takeaways

  • Register through Social Security (ssa.gov, 1-800-772-1213, or your local office), not through Medicare directly.
  • Your registration window opens three months before you turn 65 and closes three months after, giving you a seven-month period to register without penalty.
  • If you already receive Social Security benefits, you are registered automatically and do not need to take any action.
  • Part A coverage begins on the first day of the month you turn 65, or the first day of the month after you register, whichever comes later.
  • Missing the initial window can result in a permanent 10 percent increase to your Part A premiums for each full year you delayed.

What happens if you register early or late

Registering during your initial seven-month window means your Part A coverage starts with no penalty. The window is generous enough that most people can register without rushing, but the penalty for missing it is permanent and applies to your entire life as a Medicare beneficiary.

If you register after your window closes, Social Security will charge you a 10 percent premium increase for each full 12 months you delayed. That increase stays on your bill forever. For example, if you turn 65 in May but do not register until January of the following year (eight months late), you owe a 10 percent penalty. If you do not register until the following May (one year late), you owe a 10 percent penalty. If you do not register until the following August (15 months late), you still owe only a 10 percent penalty because the second full year has not passed.

The penalty does not explore if you were covered by a group health plan through your job or your spouse's job during the months you delayed. You will need to show proof of that coverage when you register.

Registering if you are not yet on Social Security

If you have not started receiving Social Security retirement benefits, you can still register for Medicare Part A through Social Security at the same time. You do not have to claim retirement benefits to get Part A. Many people register for Part A at 65 but delay claiming retirement benefits until 70 to receive a higher monthly payment.

When you contact Social Security to register for Part A, tell them you want Part A only and are not claiming retirement benefits yet. They will walk you through the process. Your Part A coverage will start at 65 regardless of when you claim retirement benefits later.

What to do after you register

After you register, Social Security will mail you a Medicare card within two weeks. Check it for errors — your name, date of birth, and Social Security number should all be correct. If something is wrong, contact Social Security right away to request a corrected card.

You do not need to do anything else to set up Part A. It begins automatically on the date Social Security tells you. You can use your Medicare card at any hospital, skilled nursing facility, or other provider that accepts Medicare. If you lose your card before it arrives or after you receive it, you can request a replacement online at ssa.gov or by calling 1-800-772-1213.

If you also want prescription drug coverage (Part D) or additional coverage beyond hospital and doctor visits, you will need to register separately for those. Part A alone covers hospital stays, skilled nursing care, hospice, and some home health services, but not doctor visits or prescriptions.

Registering if you are still working at 65

If you are still working and covered by your employer's health plan at 65, you can delay registering for Part A without penalty as long as your employer has 20 or more employees. Your employer's plan is considered primary, meaning it pays first, and Medicare pays second. You can register for Part A anytime during your employment or within eight months after you leave the job.

Once you leave your job or lose employer coverage, your initial registration window reopens. You have eight months from the date your coverage ends to register without penalty. If you wait longer than eight months, the 10 percent penalty applies.

Registering if you are on disability

If you receive Social Security Disability Insurance (SSDI), you are registered for Medicare Part A automatically after you have been on disability for 24 months. You do not need to do anything — Social Security will send you a Medicare card. Your Part A coverage begins on the 25th month of your disability.

If you have End-Stage Renal Disease (ESRD) or ALS (amyotrophic lateral sclerosis), you may be registered for Medicare Part A sooner. Contact Social Security to confirm your registration date if you have either condition.

Registering if you are not a U.S. citizen

You can register for Medicare Part A if you are a lawful permanent resident (green card holder) or have another may have access to immigration status. You will need to provide proof of legal residency when you register. Acceptable documents include a green card, an I-797 notice of action, or an employment authorization document (EAD).

If you are not sure whether your immigration status qualifies, contact Social Security before you register. They can tell you whether you are may be able to access and what documents you need to bring.

Frequently Asked Questions

Can I register for Part A online?

Yes. Go to ssa.gov, create a my Social Security account if you do not have one, and look for the Medicare registration option. You can complete the entire process online without calling or visiting an office. You will receive a confirmation number and your Medicare card will arrive by mail within two weeks.

What if I turned 65 more than three years ago and never registered?

You can still register, but you will owe a permanent 10 percent penalty on your Part A premiums. The penalty applies for the rest of your life. Register as soon as possible to stop the penalty from growing. If you had employer coverage during those years, bring proof of that coverage — it may eliminate the penalty.

Do I have to register for Part B at the same time as Part A?

No. Part A and Part B are separate. You register for Part A through Social Security. Part B (doctor visits and outpatient care) is optional and has its own registration window and rules. You can register for Part A without Part B, though most people eventually get both.

What if Social Security says I am already registered but I never applied?

If you receive Social Security retirement or disability benefits, you were registered automatically. Check your Social Security account online or call 1-800-772-1213 to confirm your registration date and when your Part A coverage begins. Your Medicare card should arrive by mail.

Can I register before I turn 65?

Yes. Your registration window opens three months before you turn 65. You can register as early as that date. Your coverage will not start until the first day of the month you turn 65, but registering early means you will not miss the important date and will not face a penalty.