When and how to sign up for Part B

Medicare Part B covers doctor visits, outpatient care, and medical equipment. You enroll during specific windows — missing them can mean paying a penalty for as long as you have Medicare. Most people sign up when they turn 65, but the exact timing depends on whether you're still working and have employer coverage.

You can enroll through Social Security, Medicare.gov, or by calling 1-800-MEDICARE. The process takes about 10 minutes online or on the phone. You'll need your Social Security number and information about any current health coverage.

Part B has a monthly premium that changes each year. In 2024, the standard premium is $164.90 per month for most people, though higher earners pay more. The amount is deducted from your Social Security check automatically once you're enrolled.

Key Takeaways

  • You must enroll in Part B during your Initial Enrollment Period, which starts three months before the month you turn 65 and ends three months after.
  • If you delay enrollment without may have access to for an exception, you'll pay a 10% penalty on your Part B premium for each year you were may be able to access but not enrolled.
  • People still working with employer coverage may be able to delay Part B without penalty if they meet specific conditions.
  • You can enroll online at Medicare.gov, by phone at 1-800-MEDICARE, or in person at your local Social Security office.

Your Initial Enrollment Period explained

Your Initial Enrollment Period is a seven-month window. It begins three months before the month you turn 65 and ends three months after. For example, if you turn 65 in June, your period runs from March through September.

During this window, you can enroll in Part B without any penalty, regardless of your health. This is the easiest time to sign up. If you enroll before the month you turn 65, your coverage starts the month you turn 65. If you enroll during or after the month you turn 65, there may be a one-month delay in your coverage start date.

If you miss this seven-month window, you enter what Medicare calls the General Enrollment Period, which runs January 1 through March 31 each year. Coverage through General Enrollment doesn't start until July 1 of that year, creating a gap. You'll also owe a late enrollment penalty.

When you can delay Part B without penalty

If you're still working at 65 and have health coverage through your employer or your spouse's employer, you may not need to enroll in Part B right away. You can delay without paying a penalty if your employer has 20 or more employees and you're actively employed.

To use this exception, you must have actual coverage — being on a family plan or a retiree plan counts, but COBRA does not. When you leave your job or lose that coverage, you have eight months to enroll in Part B without penalty. This is called your Special Enrollment Period.

If you're not sure whether your coverage qualifies, call 1-800-MEDICARE before your Initial Enrollment Period ends. Getting this wrong is expensive: if you delay without may have access to for an exception, the penalty sticks with you permanently.

How to enroll: three ways to sign up

Online at Medicare.gov: Go to Medicare.gov/sign-up-change-plans. You'll need to create or log into your Medicare account. The site walks you through each question and you can save your progress. Enrollment is when ready, though confirmation by mail takes about two weeks.

By phone: Call 1-800-MEDICARE (1-800-633-4227). Representatives are available Monday through Friday, 8 a.m. to 8 p.m. Eastern time, and Saturday 9 a.m. to 1 p.m. Eastern time. Have your Social Security number and insurance information ready. The call 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 or legal residency, and information about any current coverage. No appointment is needed, though wait times vary by location.

What happens after you enroll

Once you enroll, you'll receive a Medicare card in the mail within two weeks. This card shows your Medicare number and which parts of Medicare you have. Keep it with you when you see doctors or go to the hospital.

Your Part B coverage starts on the first day of the month you enrolled, or the following month if you enrolled after the 15th. Your first premium payment is deducted from your Social Security check, usually the month after your coverage begins. If you don't receive Social Security, Medicare will send you a bill.

Once Part B is active, you can also enroll in Part D (prescription drug coverage) and Medigap (supplemental coverage) if you want them. Part D has its own enrollment important date, so don't delay if you need it.

Late enrollment penalties and how they work

If you miss your Initial Enrollment Period and don't may have access to for an exception, Medicare charges a late enrollment penalty. The penalty is 10% of the Part B premium for each full year you were may be able to access but not enrolled. If you were may be able to access for two years and didn't enroll, you pay 20% extra on top of your regular premium.

The penalty is permanent — you pay it for as long as you have Part B, even if you move to a different state or change plans. For example, if the standard premium is $164.90 and you were late by two years, you'd pay an extra $32.98 per month forever.

The only way to avoid the penalty is to prove you had may have access to coverage (employer coverage, TRICARE, Veterans benefits, or certain other plans) during the time you didn't have Part B. You'll need documents from that coverage to show Social Security or Medicare.

Documents you'll need to have ready

Before you enroll, gather these items so the process goes faster:

  • Your Social Security number
  • Proof of citizenship or legal residency (passport, birth certificate, or naturalization papers)
  • Information about any current health coverage (employer plan, COBRA, Medicaid, or Veterans benefits)
  • Your address and phone number

If you're enrolling by phone or in person, having these ready means you won't have to call back or make a second trip. If you're enrolling online, you can look them up as you go — the website doesn't time out if you pause.

Frequently Asked Questions

What if I turn 65 while I'm still working?

You can delay Part B if your employer has 20 or more employees and you have actual health coverage through that job. When you leave work or lose that coverage, you have eight months to enroll without penalty. If your employer has fewer than 20 employees, you should enroll during your Initial Enrollment Period even if you're still working.

Can I enroll in Part B after I turn 65 if I missed the important date?

Yes, but only during General Enrollment (January 1 through March 31 each year), and your coverage won't start until July 1. You'll also owe a late enrollment penalty. If you have a may have access to reason for missing the important date — such as incorrect information from Social Security — contact Medicare to ask about a Special Enrollment Period.

Do I have to enroll in Part B if I have Veterans benefits or TRICARE?

No, but you should check with your Veterans or TRICARE representative first. Some people with these benefits still choose to enroll in Part B for broader coverage. If you decide later that you want Part B, you may owe a late penalty unless you may have access to for an exception.

What if I enrolled in Part B but want to drop it?

You can drop Part B, but only during the General Enrollment Period (January 1 through March 31), and your coverage ends on June 30. If you drop it and want it back later, you'll owe a late enrollment penalty. Most people should keep Part B once they enroll.

How much does Part B cost besides the monthly premium?

Part B has a yearly deductible (currently $240 in 2024) and you pay 20% of the cost for most services after you meet the deductible. Costs vary by service. Your actual out-of-pocket expenses depend on how much care you use and whether you have supplemental coverage like Medigap.