Sign up for Medicare Part B during your Initial Enrollment Period or during General Enrollment

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 on the first day of your birth month. This is the only time you can avoid a permanent penalty on your Part B premium.

If you miss your Initial Enrollment Period, you can still sign up during General Enrollment, which runs from January 1 to March 31 each year. Coverage begins July 1 of that year. However, you will pay a higher premium for as long as you have Part B — typically 10 percent more for each full year you delayed.

There is one exception: if you were covered by an employer health plan when you turned 65, you may have a Special Enrollment Period of eight months after that coverage ends. During this window, you can sign up without the penalty, even if you miss your Initial Enrollment Period.

Key Takeaways

  • Your Initial Enrollment Period is seven months long — three months before your 65th birthday, your birth month, and three months after — and this is the only time to avoid a permanent premium penalty.
  • If you sign up during your Initial Enrollment Period, Part B coverage starts on the first day of your birth month; if you sign up during General Enrollment (January through March), coverage starts July 1.
  • Missing your Initial Enrollment Period triggers a 10 percent premium increase for each full year you delayed, and this penalty stays with you for life.
  • If you had employer health insurance when you turned 65, you have eight months after that coverage ends to sign up without penalty, even if you missed your Initial Enrollment Period.

How to find your Initial Enrollment Period dates

Your Initial Enrollment Period depends on your birth month. The window always opens three months before the month you turn 65 and closes three months after. For example, if you turn 65 in June, your Initial Enrollment Period runs from March through September.

You do not have to wait for Medicare to contact you. You can sign up as soon as your Initial Enrollment Period begins — you do not have to wait until your birth month or until you turn 65. Signing up early gives you time to choose your plan and make sure your coverage starts on time.

Medicare will send you a notice in the mail about two months before your 65th birthday, but do not rely on this to know your dates. Write down your seven-month window now so you do not miss it.

What happens if you sign up late

If you sign up after your Initial Enrollment Period ends and you did not have employer coverage, you will owe a late enrollment penalty. This is a permanent increase to your Part B premium — usually 10 percent for each full year you were may be able to access but not signed up.

The penalty is calculated from the month your Initial Enrollment Period ended. If your period ended in September and you sign up in December, you owe three months of penalty. If you sign up two years later, you owe 20 percent more on your premium for the rest of your life.

This penalty does not go away. Even if you sign up years later, you will keep paying it every month. The only way to avoid it is to sign up during your Initial Enrollment Period or to have had employer coverage that qualifies you for a Special Enrollment Period.

Where to sign up for Part B

You can sign up online at Medicare.gov, by phone at 1-800-MEDICARE (1-800-633-4227), or in person at your local Social Security office. You will need your Social Security number and information about any current health coverage you have.

If you are already receiving Social Security benefits, you may be signed up for Part B automatically when you turn 65. Check your Social Security statement or call Social Security to confirm. If you do not want Part B, you must decline it in writing before your coverage would start.

If you are not yet receiving Social Security, you must sign up for Part B yourself. Do not assume you are enrolled — check your status at Medicare.gov or call to be sure.

The difference between signing up early and signing up late in your Initial Enrollment Period

Signing up early in your Initial Enrollment Period gives you a buffer. If you sign up three months before your 65th birthday, you have time to receive your Medicare card, review your coverage, and contact Medicare if something is wrong. If you sign up in your birth month or the month after, you risk delays that could leave you without coverage on the date you expected.

The coverage start date is the same regardless of when you sign up during your Initial Enrollment Period — it is always the first day of your birth month. But the processing time varies. Signing up early means your card and welcome packet arrive with time to spare.

If you wait until the last month of your Initial Enrollment Period, you may not receive your card before your coverage starts. This can create confusion with your doctors and pharmacies. Plan to sign up at least one month before your birth month.

Special situations: employer coverage and disability

If you are still working and covered by your employer's health plan when you turn 65, you do not have to sign up for Part B right away. You have eight months after your employer coverage ends to sign up without a penalty. This is called a Special Enrollment Period.

If you are under 65 and receiving Social Security disability benefits, you are automatically enrolled in Medicare after 24 months of receiving benefits. You do not need to sign up; Medicare will contact you. Part B coverage begins automatically, and you cannot decline it.

If you are on dialysis or have had a kidney transplant, you may be able to sign up for Medicare before 65. Contact Social Security or Medicare directly to learn whether you may have access to.

Frequently Asked Questions

What if I turned 65 and did not sign up — can I still get Part B without a penalty?

Only if you had employer health insurance when you turned 65. You have eight months after that coverage ends to sign up without penalty. If you did not have employer coverage, you will owe a late enrollment penalty equal to 10 percent of your Part B premium for each full year you delayed. This penalty is permanent.

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

Not if you have employer coverage. You can delay Part B and sign up later without penalty as long as you sign up within eight months of losing your employer coverage. If you do not have employer coverage, you should sign up during your Initial Enrollment Period to avoid a penalty.

What if I miss the important date by just a few days?

A few days late is still late. Your Initial Enrollment Period is seven months long — if you sign up after it ends, you will owe a late enrollment penalty. There is no grace period. Mark your important date on a calendar and sign up before the last day of your third month after your birth month.

Can I change my mind and drop Part B after I sign up?

Yes, but only during General Enrollment (January 1 to March 31). If you drop Part B and later want it back, you will owe a late enrollment penalty unless you have employer coverage that qualifies you for a Special Enrollment Period. Think carefully before declining Part B.

If I am on Social Security disability, do I still have an Initial Enrollment Period for Part B?

No. You are automatically enrolled in Medicare Part B after 24 months of receiving disability benefits. You cannot decline it, and you do not have a choice of enrollment periods. Your coverage begins automatically, and you will receive your Medicare card in the mail.