When and how to sign up for Part B

You sign up for Medicare Part B (medical insurance) through Social Security, either online at Medicare.gov, by phone, or in person at your local Social Security office. The timing matters: you have a window of time around your 65th birthday when you can join without penalty, and missing that window can cost you more later.

Most people become may be able to access for Medicare the month they turn 65. Your initial enrollment period runs for three months before the month you turn 65, the month itself, and three months after — a total of seven months. If you sign up during this window, your coverage typically starts the first day of the month you turn 65.

If you are still working and covered by your employer's health plan, you may be able to delay Part B without penalty. This is called having creditable coverage. You will need to show proof that your employer plan is active when you do sign up later, so keep your insurance documents.

Key Takeaways

  • You can sign up for Part B online at Medicare.gov, by calling Social Security at 1-800-772-1213, or at your local Social Security office.
  • Your initial enrollment period is seven months long: three months before you turn 65, the month you turn 65, and three months after.
  • If you miss your initial enrollment window and do not have employer coverage, you will pay a permanent penalty on your Part B premium for as long as you have Medicare.
  • If you are still working with employer health insurance, you can delay Part B and sign up later without penalty, but you must have proof of that coverage.

What documents you need to sign up

You will need your Social Security number and proof of citizenship or legal residency. Have your birth certificate, passport, or naturalization papers ready. If you are signing up by phone or online, you can provide this information verbally or upload documents.

If you are delaying Part B because you have employer coverage, bring or upload a copy of your current health insurance card and any documents showing your employer plan is active. Social Security will ask for your employer's name and the date your coverage began.

The cost of Part B and when you pay

Part B has a monthly premium that changes each year. In 2024, the standard premium is $164.90 per month, but higher earners pay more through an income-related adjustment. The exact amount depends on your income from two years prior, so when you first sign up, Social Security will tell you what you will pay.

You also pay a yearly deductible (currently $240) before Part B starts covering services, and then you typically pay 20 percent of the cost for most doctor visits and outpatient care. These costs are separate from what you pay for Part A (hospital insurance).

Your premium is usually taken directly from your Social Security check each month. If you are not yet receiving Social Security, you will receive a bill in the mail.

What happens if you miss your enrollment window

If you do not sign up during your initial seven-month window and you do not have employer coverage, you will have to wait until the next General Enrollment Period, which runs January 1 through March 31 each year. Your coverage would then start July 1.

More importantly, you will pay a permanent penalty. Your Part B premium increases by 10 percent for each full year you were may be able to access but not enrolled. This penalty stays with you for life, even if you sign up years later. For example, if you were may be able to access at 65 but did not sign up until age 68, you would pay an extra 30 percent on your premium forever.

The only way to avoid this penalty is to have had creditable coverage (like an active employer plan) during the time you were not enrolled in Part B.

Signing up if you are already receiving Social Security

If you are already getting Social Security benefits when you turn 65, you are usually signed up for Part B automatically. You will receive a Medicare card in the mail about two weeks before your coverage starts. You do not need to do anything unless you want to decline Part B, which you can do by contacting Social Security.

If you decline Part B at 65 because you have employer coverage, make sure to sign up again when your employer coverage ends. You will have a special enrollment period of two months after your coverage ends to sign up without penalty.

Signing up online, by phone, or in person

Online: Go to Medicare.gov and create a "My Medicare" account. You can sign up for Part B through this account. The process takes about 15 minutes and you can save your progress and come back later.

By phone: Call Social Security at 1-800-772-1213. Representatives are available Monday through Friday, 7 a.m. to 7 p.m. Eastern time. Have your Social Security number and citizenship documents ready. The call usually takes 10 to 15 minutes.

In person: Visit your local Social Security office. You can find the nearest one at ssa.gov/locator. Bring your Social Security card, proof of citizenship, and any documents about employer coverage if you have it. No appointment is needed, but wait times vary.

What to do after you sign up

After you sign up, you will receive a Medicare card in the mail 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 Medicare at 1-800-MEDICARE (1-800-633-4227).

Your Part B coverage starts on the first day of the month you are approved, or the first of the following month if you sign up after the 15th. You can start using your coverage as soon as it begins. Show your Medicare card to your doctor's office and any other providers.

If you have questions about what Part B covers or what you will pay for specific services, call 1-800-MEDICARE. They can also help you understand whether you need additional coverage like a Medigap or Medicare Advantage plan.

Frequently Asked Questions

Can I sign up for Part B after I turn 65 if I missed my enrollment window?

Yes, you can sign up during the General Enrollment Period (January 1 through March 31 each year), and your coverage starts July 1. However, you will pay a permanent 10 percent penalty on your premium for each year you were may be able to access but not enrolled, unless you had employer coverage during that time.

What if I am still working and have health insurance through my job?

You can delay Part B without penalty as long as your employer plan is active. When you leave your job or your coverage ends, you have two months to sign up for Part B without penalty. Keep proof of your employer coverage in case you need it later.

Do I have to sign up for Part A and Part B at the same time?

No. Part A (hospital insurance) is usually automatic at 65 if you are receiving Social Security. Part B (medical insurance) is separate, and you choose whether to enroll. However, if you delay Part B without creditable coverage, you will pay a penalty.

What if I made a mistake on my process?

Contact Social Security at 1-800-772-1213 or visit your local office. They can correct errors on your process. If your coverage has already started, Medicare can also fix errors on your card — call 1-800-MEDICARE.

Can my spouse sign up for Part B at the same time I do?

Yes. Each person has their own enrollment period based on their own birthday. Your spouse can sign up during their own seven-month window. You can explore together at the same Social Security office or online, but each process is separate.