Medicare has three separate sign-up periods, and missing the main one costs you money for life

Your first chance to sign up for Medicare is the seven-month window that starts three months before you turn 65 and ends three months after. If you sign up during this Initial Enrollment Period, your coverage begins the month you turn 65 (or the month after, depending on when in the month you were born). Miss this window, and you will pay a permanent penalty on your Part B and Part D premiums — 10 percent more for each year you delayed, for as long as you have Medicare.

The other two periods are narrower and explore only if you did not sign up the first time. The General Enrollment Period runs January 1 through March 31 each year, and coverage starts July 1. The Special Enrollment Period opens if you have a may have access to life event — losing employer coverage, moving to a different state, or getting married — and you have a limited window (usually 60 days) to sign up without penalty.

Key Takeaways

  • 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 the Initial Enrollment Period and do not have may have access to employer coverage, you will pay a 10 percent penalty on Part B and Part D premiums for every year you delayed, permanently.
  • The General Enrollment Period (January 1 through March 31) is open to anyone, but coverage does not start until July 1, leaving you uninsured for months.
  • A Special Enrollment Period opens if you lose employer coverage or experience certain life changes, and you have about 60 days to sign up without penalty.
  • If you are still working and covered by your employer's health plan, you may be able to delay Medicare without penalty — but you must document this with your employer.

The Initial Enrollment Period: your main window

The Initial Enrollment Period is the only time you can sign up for Medicare without facing a permanent financial penalty. It spans seven months total: it starts three months before the month you turn 65, includes the month you turn 65, and runs through three months after.

For example, if you turn 65 in June, your Initial Enrollment Period runs from March through September. You can sign up anytime during those seven months. If you sign up in March, your coverage begins in June. If you sign up in June, your coverage begins in June. If you sign up in September, your coverage begins in October.

The exact start date of your coverage depends on when you sign up and when your birthday falls. Medicare.gov has a tool that shows your specific dates based on your birth date. Write down your seven-month window now — do not rely on a reminder later.

What the penalty is and how it works

If you do not sign up during your Initial Enrollment Period and you do not have a may have access to reason to delay, you will pay a late enrollment penalty on Part B and Part D for the rest of your life. The penalty is 10 percent of the standard premium for each full year you were may be able to access but did not sign up.

The Part B standard premium in 2024 is $164.90 per month. A 10 percent penalty adds $16.49 per month. If you delay two years, the penalty is 20 percent, or $32.98 per month. This penalty does not go away when you finally sign up — it stays on your bill every month you have Medicare.

Part D (prescription drug coverage) has the same penalty structure. If you go without Part D coverage and then sign up later, you pay 1 percent of the national base beneficiary premium for each month you were without it. This also stays on your bill permanently.

The only exception is if you had creditable coverage through an employer or union while you were working. Creditable coverage means your employer's health plan was at least as good as Medicare. If you had this coverage, you can delay Medicare without penalty, but you must sign up within 63 days of losing that coverage.

The General Enrollment Period: the backup option with a gap

If you miss your Initial Enrollment Period and do not have creditable employer coverage, the General Enrollment Period is open to anyone. It runs January 1 through March 31 every year. You can sign up anytime during those three months.

The catch is timing. If you sign up during the General Enrollment Period, your coverage does not start until July 1. If you sign up in January, you have six months with no Medicare coverage. If you sign up in March, you have four months with no coverage. You will still owe the late enrollment penalty on top of this gap.

This is why the General Enrollment Period is a last resort, not a plan. Use it only if you missed your Initial Enrollment Period and have no other option.

Special Enrollment Periods: when you can sign up outside the main windows

A Special Enrollment Period opens if you experience certain life events that change your insurance situation. The most common may have access to events are losing employer coverage, moving to a different state, getting married or divorced, or becoming a U.S. citizen.

When you have a may have access to event, you usually have 60 days from the date the event happens to sign up for Medicare without penalty. Coverage typically starts the month after you sign up. You do not have to wait for January 1 or your birthday.

The key is documenting the event. If you lost employer coverage, keep your termination letter or the letter from your employer saying coverage ended. If you moved, keep proof of your new address. When you sign up, you will need to show this documentation to prove you may have access to for the Special Enrollment Period.

How to sign up and where to do it

You can sign up for Medicare through Medicare.gov, by phone at 1-800-MEDICARE, or in person at your local Social Security office. You will need your Social Security number, proof of citizenship or legal residency, and information about any current health coverage you have.

If you are signing up online, go to Medicare.gov and look for the enrollment section. The process takes about 15 minutes. If you call, a representative will walk you through the same questions. If you go in person, bring your documents and expect to spend 30 to 45 minutes.

Sign up as soon as your Initial Enrollment Period opens. Do not wait until the last month. If there are any problems with your process, you will have time to fix them before your coverage is supposed to start.

If you are still working: delaying Medicare without penalty

If you are still working and covered by your employer's health plan, you may be able to delay Medicare without paying the late enrollment penalty. This is called creditable coverage. Your employer's plan must be at least as good as Medicare — most employer plans are.

To use this exception, you must sign up for Medicare within 63 days of losing your employer coverage. This means you can work past 65, stay on your employer's plan, and sign up for Medicare later without penalty — as long as you do it within the 63-day window after you leave the job or lose coverage.

Get a letter from your employer or benefits department stating that your health plan is creditable coverage and the date it ends. Keep this letter. When you sign up for Medicare after you retire, you will need to show it to prove you had a valid reason to delay.

Frequently Asked Questions

What if I turn 65 on the first or last day of the month?

Your Initial Enrollment Period is still seven months long. If you turn 65 on the first day of the month, your period starts three months before. If you turn 65 on the last day of the month, your period still covers three months before and three months after. Medicare.gov will show your exact dates when you enter your birth date.

Can I sign up for Part A only and delay Part B?

Yes, but only if you have creditable coverage through an employer. If you do not have employer coverage, you must sign up for both Part A and Part B during your Initial Enrollment Period to avoid the Part B penalty. Part A (hospital insurance) rarely has a penalty, but Part B (medical insurance) does.

What happens if I sign up late but then move to a different state?

Moving to a different state opens a Special Enrollment Period. You have 60 days from your move to sign up without the late enrollment penalty. Keep proof of your new address (a utility bill or lease) to show when you sign up.

Do I have to sign up for Part D during my Initial Enrollment Period?

No, but if you do not have prescription drug coverage and you delay Part D, you will pay a penalty when you finally sign up. The penalty is 1 percent of the national base premium for each month you were without it. If you do not take prescription drugs, you can skip Part D, but once you need it, the penalty applies.

Can I change my mind after I sign up?

Yes. You have until December 31 of the year you turn 65 to change your Medicare choices. After that, you can only make changes during the annual Open Enrollment Period (October 15 through December 7) or if you have a may have access to life event.