How to sign up for Medicare Part A and Part B, step by step

Will you be signed up automatically?

Already getting Social Security or Railroad Retirement benefits

If they started at least 4 months before you turn 65, you get Part A and Part B automatically. Your card arrives about 3 months before your birthday. You can turn Part B down by following the instructions that come with it, for example if you have coverage from a current job (yours or your spouse's) that lets you wait. Check first: turning it down otherwise can mean a gap and a lifelong penalty.

Applying for Social Security within 3 months before you turn 65, or later

Part A comes automatically with the benefits, but Part B doesn't: you choose it on the application.

Not getting benefits yet

You have to sign up. Most people who are still working, or waiting to claim Social Security, are in this group.

Under 65 with a disability

Automatic after 24 months of disability benefits, or the month benefits start if you have ALS. Kidney failure (ESRD) requires an application.

Puerto Rico

Part A is automatic, but you must sign up for Part B (form CMS-40B).

When to sign up

Your Initial Enrollment Period is 7 months: the 3 months before the month you turn 65, that month, and the 3 months after. (If your birthday is on the 1st, everything moves a month earlier.)

Signing up in the first 3 months is the only way to have Part B start exactly when you turn 65. Premium-free Part A can be backdated to the month you turn 65; if you have an HSA, see working past 65. If you're covered by a current job, you may be able to wait; check first.

How to sign up

1. 1

   Online (fastest)

   Go to SSA.gov/medicare/sign-up and sign in to, or create, a my Social Security account. You can apply for Part A and Part B, or Part A only. You'll need your Social Security number, your place of birth, and the start and end dates of any group health plans you've had through a job since 65. Social Security will tell you if it needs documents.
2. 2

   By phone

   Call Social Security at 1-800-772-1213 (TTY 1-800-325-0778), Monday to Friday, 8 a.m. to 7 p.m. Ask to sign up for Medicare Part A and Part B, or Part A only.
3. 3

   In person

   Visit your local Social Security office; find it at SSA.gov/locator. An appointment can save waiting.
4. 4

   Railroad workers

   Sign up through the Railroad Retirement Board: 1-877-772-5772 (TTY 1-312-751-4701) or RRB.gov.

Already have Part A and want Part B

Apply online with your Medicare Number and an email address, or send form CMS-40B to Social Security. Don't use CMS-40B if you don't have Part A yet.

Leaving job coverage

Add form CMS-L564, which the employer fills in to confirm your coverage.

Prevented from signing up by a disaster, an employer's error or another exceptional situation

Ask Social Security about a special enrollment period (form CMS-10797).

Your Medicare card

If you signed up yourself, a welcome package with your red, white and blue Medicare card is usually mailed about 2 weeks after you sign up. The card shows your 11-character Medicare Number and the dates Part A ("Hospital") and Part B ("Medical") start.

Keep it safe

Show it to doctors and hospitals, but only give your Medicare Number to people you know should have it.

Online account

Create one at Medicare.gov/account. For 2027 you can sign in with ID.me, CLEAR or Login.gov.

Lost card

Replacements are free: print one from your Medicare.gov account or call 1-800-MEDICARE (1-800-633-4227).

Part B costs $202.90 a month in 2026 (the standard premium), with a $283 deductible. If you get Social Security, it's taken from your benefit; otherwise Medicare bills you. All Medicare costs.

What to choose next

Part A and Part B are Original Medicare. Most people add coverage, and each choice has its own window:

A drug plan (Part D)

The same 7 months as your Initial Enrollment Period. Waiting without other creditable drug coverage can mean a lifelong penalty.

Or a Medicare Advantage plan

From 3 months before the month you have both Part A and Part B until the end of the second month after that month (or the end of your 7-month window, if later).

A Medigap policy

Your best time is the 6 months starting the first month you have Part B and are 65 or older. Federal law says insurers can't turn you down or charge you more because of your health during this window. Some states give extra protections.

A licensed agent can compare plans with you at no cost, or your state's free SHIP counselor can help. Agents may not offer every plan in your area; Medicare.gov/plan-compare and 1-800-MEDICARE list them all. Advantage or Medigap?

Mistakes to avoid

• Assuming Part B started when you applied for Social Security at or after 65. Check your card or letter.
• Waiting for COBRA or retiree coverage to end before signing up for Part B. Neither counts as job coverage.
• Delaying Part B at a job with fewer than 20 employees: Medicare pays first there.
• Putting money into an HSA after Medicare starts, including the months Part A is backdated.
• Letting your Medigap window go to waste. It starts when Part B starts, even if you still have job coverage, lasts 6 months and can't be saved for later.
• Trusting old articles about coverage start dates. Delays were shortened on January 1, 2023.

Common questions

Keep reading

• Turning 65: a Medicare checklist, month by monthWhat to do before and after your 65th birthday: when to sign up, what to do if you're still working, your one-time Medigap window, and the deadlines that carry lifelong penalties.
• Medicare if you keep working past 65: what to sign up for, and whenWhether you need Part A and Part B while you're covered at work, why employer size matters, what to do about an HSA, and how to sign up without a penalty when you retire.
• Medicare enrollment periods: when you can sign up or switchEvery Medicare enrollment window in one place: turning 65, the fall Annual Enrollment Period, the January–March change, Medigap open enrollment, special periods and late penalties.