Sign up for Medicare Part B during your Initial Enrollment Period or face permanent penalties

Your Initial Enrollment Period is a seven-month window that starts three months before the month you turn 65 and ends three months after. If you sign up during this window, your Part B coverage begins the month you turn 65 (or the first day of the month after you sign up, whichever is later). If you miss this window, you can still sign up later, but you will pay a higher monthly premium for as long as you have Medicare — the penalty is 10 percent for each full year you delayed, and it does not go away.

The only exception is if you have creditable coverage through an employer or union when you turn 65. Creditable coverage means your employer or spouse's employer is still actively covering you in a health plan. If you have creditable coverage, you can delay Part B without penalty as long as you stay covered. You must sign up within eight weeks of losing that coverage or retiring, whichever comes first.

Key Takeaways

  • Your Initial Enrollment Period runs for seven months: three months before you turn 65, the month you turn 65, and three months after.
  • If you miss your Initial Enrollment Period and do not have creditable coverage through an employer, you will pay a permanent 10 percent monthly premium increase for each year you delayed.
  • If you have active employer coverage when you turn 65, you can delay Part B without penalty, but you must sign up within eight weeks of losing that coverage.
  • You can sign up for Part B through Social Security, Medicare.gov, or your local Social Security office.
  • Part B covers doctor visits, outpatient care, and some preventive services, and it requires a monthly premium separate from Part A.

What counts as creditable coverage and why it matters

Creditable coverage is health insurance through your job or your spouse's job that is still active when you turn 65. It includes employer group health plans, union plans, and COBRA coverage (the temporary continuation of your employer plan after you leave). It does not include retiree health plans that have already ended, individual plans you bought yourself, or Medicaid.

If you have creditable coverage, you do not have to sign up for Part B at 65. You can stay on your employer plan and sign up for Part B later without the permanent penalty. However, you must sign up within eight weeks of the date your coverage ends or the date you retire, whichever happens first. If you miss that eight-week window, the penalty applies.

To prove you had creditable coverage, keep your insurance card and any letters from your employer or insurance company that state the dates you were covered. You will need this proof when you sign up for Part B.

Your Initial Enrollment Period: the seven-month window

Your Initial Enrollment Period starts on the first day of the third month before you turn 65 and ends on the last day of the third month after you turn 65. For example, if you turn 65 in June, your Initial Enrollment Period runs from March 1 through September 30.

During this window, you can sign up for Part B without penalty. The month your coverage begins depends on when you sign up. If you sign up during the first three months of your Initial Enrollment Period (before the month you turn 65), Part B coverage starts the month you turn 65. If you sign up in the month you turn 65 or later, coverage starts the first day of the month after you sign up.

You do not have to sign up for Part B during your Initial Enrollment Period if you have creditable coverage, but if you do not have creditable coverage and you miss this window, you will face a permanent penalty.

How the Part B penalty works and how long it lasts

If you miss your Initial Enrollment Period and do not have creditable coverage, Medicare adds 10 percent to your Part B premium for each full 12-month period you were may be able to access but not signed up. This penalty is permanent — it stays with you for as long as you have Medicare, even if you move to a different plan.

For example, if you turn 65 in June 2024 and do not sign up for Part B until January 2026, you delayed for 19 months. That is one full 12-month period plus seven months. You would pay a 10 percent penalty on your Part B premium for life. If you delayed for three full years, the penalty would be 30 percent.

The only way to avoid this penalty is to sign up during your Initial Enrollment Period or within eight weeks of losing creditable coverage. There is no way to have the penalty removed once it is applied.

How to sign up for Part B

You can sign up for Part B through three routes: Social Security, Medicare.gov, or your local Social Security office in person.

Through Social Security online: Go to ssa.gov, sign in to your account, and look for the option to explore for Medicare. You can complete the process online and submit it without leaving home. Social Security will contact you if they need more information.

Through Medicare.gov: Go to Medicare.gov and select "Sign up for Medicare." You can explore online, by phone at 1-800-MEDICARE, or by mail. The online process takes about 15 minutes.

In person: Visit your local Social Security office with your Social Security card and proof of citizenship or legal residency. You can find your local office at ssa.gov/locator.

No matter which route you choose, have your Social Security number, date of birth, and citizenship or residency documents ready. If you are signing up after 65, also have proof of any creditable coverage you had.

What Part B covers and why you might want it

Part B covers doctor visits, outpatient hospital care, medical equipment, and some preventive services like screenings and vaccines. It also covers physical therapy, occupational therapy, and some mental health services. Part B does not cover dental, vision, or hearing care, and it does not cover prescription drugs (that is Part D).

Part B requires a monthly premium, which changes each year. In 2024, the standard premium is $164.90 per month, but it varies based on your income. You also pay a yearly deductible ($240 in 2024) and then 20 percent of the cost of most services after that.

If you have very low income, you may be able to get help paying your Part B premium through a program called Medicaid or the Medicare Savings Program. Your state's Medicaid office can tell you whether you may have access to.

Special situations: when you can sign up outside your Initial Enrollment Period

If you miss your Initial Enrollment Period but have a good reason, you may be able to sign up during a Special Enrollment Period without penalty. Reasons that may have access to include losing employer coverage, moving out of your plan's service area, or having your plan end. You typically have two months from the date your coverage ends to sign up.

If you are still working and your employer has 20 or more employees, you may also be able to delay Part B. This is called the Group Health Plan exception. You can stay on your employer plan and sign up for Part B later without penalty, as long as you sign up within eight weeks of retiring or losing coverage.

If you think you have a reason to sign up outside your Initial Enrollment Period, contact Social Security or Medicare to ask. They can tell you whether your situation qualifies for a Special Enrollment Period.

Frequently Asked Questions

What happens if I turn 65 but do not sign up for Part B?

If you do not have creditable coverage and do not sign up during your Initial Enrollment Period, you will pay a permanent 10 percent monthly premium increase for each year you delayed. You can sign up later, but the penalty stays with you for life. The only exception is if you have active employer coverage when you turn 65.

Can I sign up for Part B after I turn 65?

Yes, you can sign up for Part B at any time after you turn 65. However, if you miss your Initial Enrollment Period and do not have creditable coverage, you will pay a permanent penalty. If you have creditable coverage, you can sign up within eight weeks of losing it without penalty.

Do I have to sign up for Part B if I am still working?

If your employer has 20 or more employees and you are still actively working, you can delay Part B without penalty. You must sign up within eight weeks of retiring or losing your employer coverage. If your employer has fewer than 20 employees, you should sign up during your Initial Enrollment Period to avoid the penalty.

What if I miss my Initial Enrollment Period but have a good reason?

You may be able to sign up during a Special Enrollment Period if you lost employer coverage, moved, or had your plan end. Contact Social Security or Medicare to explain your situation and ask whether you may have access to. If you do, you can sign up without penalty.

How much does Part B cost?

The standard Part B premium in 2024 is $164.90 per month, but it changes each year and varies based on your income. You also pay a yearly deductible ($240 in 2024) and 20 percent of most services after that. If you have low income, you may may have access to for help paying your premium through Medicaid or the Medicare Savings Program.