The three enrollment periods for Medicare

Medicare has three separate windows when you can sign up or make changes to your coverage. Missing these windows can mean waiting months before you can enroll, or paying a penalty for the rest of your time on Medicare. The three periods are the Initial Enrollment Period (when you first become may be able to access), the General Enrollment Period (a backup window each year), and the Special Enrollment Period (when life changes happen).

Each period has different rules about what you can change and when coverage starts. Understanding which period applies to you now will help you avoid gaps in coverage or unnecessary costs.

Key Takeaways

  • Your Initial Enrollment Period is the seven-month window centered on your 65th birthday — three months before, the month of, and three months after.
  • If you miss your Initial Enrollment Period, you can only sign up during the General Enrollment Period (January 1 to March 31 each year), and your coverage will not start until July 1.
  • A Special Enrollment Period opens when you have a may have access to life event, such as losing employer coverage, moving to a new state, or becoming a U.S. citizen.
  • Late enrollment penalties are added to your monthly premium for as long as you have Medicare if you miss your Initial Enrollment Period without a may have access to reason.

Initial Enrollment Period: Your first chance to sign up

Your Initial Enrollment Period is a seven-month window that 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 time, you can sign up for Part A (hospital insurance), Part B (medical insurance), or both.

Signing up during your Initial Enrollment Period is important because it is the only time you can enroll in Part A and Part B without a penalty, no matter when you were born or what your health is. If you are still working and have health insurance through your employer, you may be able to delay Part B without penalty — but you must contact Social Security to request this delay in writing.

Coverage typically starts on the first day of the month in which you turn 65, or the first day of the following month if you sign up after the 15th of any month during your period.

General Enrollment Period: The yearly backup window

The General Enrollment Period runs from January 1 through March 31 each year. If you did not sign up during your Initial Enrollment Period, you can sign up during the General Enrollment Period. However, there are two important catches: coverage does not start until July 1, and you will owe a late enrollment penalty.

The late enrollment penalty for Part B is 10 percent of the standard premium for each full year you were may be able to access but did not sign up. This penalty is added to your monthly bill for as long as you have Medicare. For example, if you were may be able to access for three years before signing up, your penalty would be 30 percent of the standard premium, added to every monthly payment going forward.

The General Enrollment Period is also when you can switch between Original Medicare and Medicare Advantage plans, or drop Part D prescription drug coverage — but only if you are already enrolled in Medicare.

Special Enrollment Period: When life changes open a window

A Special Enrollment Period is an extra enrollment window that opens when you have a may have access to life event. Unlike the other two periods, a Special Enrollment Period can happen at any time of year and gives you a specific number of months to act.

Common may have access to events include losing employer health coverage, moving to a new state, becoming a U.S. citizen, getting married or divorced, or having a change in income that affects your Part B premium. If you are turning 65 while still employed and covered by your employer's group health plan, you have an eight-month Special Enrollment Period after your employment or coverage ends to sign up for Part B without penalty.

The length of your Special Enrollment Period depends on the reason for the change — most are two to three months long. Coverage dates also vary: some changes allow coverage to start as early as the first day of the month you request it, while others have a later start date. You will need to contact Medicare directly or speak with a Social Security representative to confirm your specific dates.

What happens if you miss all three periods

If you do not sign up during your Initial Enrollment Period and do not have a may have access to reason for a Special Enrollment Period, you must wait for the next General Enrollment Period to sign up. This means you could go without Medicare coverage for months, and you will owe the late enrollment penalty when you finally do enroll.

The penalty is permanent — it does not go away after a certain number of years. Even if you sign up years later, the penalty will be calculated based on how long you were may be able to access without coverage and will be added to your monthly premium for the rest of your life on Medicare.

There is one exception: if you can show that you had continuous creditable coverage (health insurance that is at least as good as Medicare) from another source during the time you were not enrolled, you may not owe a penalty. You will need to provide proof of this coverage to Medicare.

How to sign up during each period

For your Initial Enrollment Period or a Special Enrollment Period, you can sign up online at Medicare.gov, by phone at 1-800-MEDICARE (1-800-633-4227), by mail, 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.

For the General Enrollment Period, the process is the same, but remember that coverage will not start until July 1 even if you sign up in January or February. If you are already on Medicare and want to make changes during the General Enrollment Period, you can also contact your current plan directly.

If you are unsure which period you are in or whether you have a may have access to reason for a Special Enrollment Period, call Social Security at 1-800-772-1213 (TTY 1-800-325-0778) before you sign up. They can tell you exactly when your coverage would start and whether you would owe a penalty.

Frequently Asked Questions

What if I turn 65 while I am still working?

You can delay signing up for Part B without penalty if you are covered by your employer's health plan and are still actively working. You have an eight-month Special Enrollment Period after you leave your job or lose coverage to sign up for Part B. Contact Social Security before you retire to request the delay in writing.

Can I change my Medicare plan outside of these enrollment periods?

No, unless you have a may have access to life event that opens a Special Enrollment Period. If you are unhappy with your current plan, you must wait for the next General Enrollment Period (January 1 to March 31) to make changes. The exception is if you are in a Medicare Advantage plan during the first three months of the year — you can switch to Original Medicare or another Advantage plan.

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

No. You can sign up for Part A without Part B, or Part B without Part A, during your Initial Enrollment Period. However, if you delay Part B, you must request this delay in writing with Social Security. Otherwise, you will be automatically enrolled in both.

What counts as a may have access to life event for a Special Enrollment Period?

Common may have access to events include losing employer coverage, moving out of your plan's service area, becoming a U.S. citizen, getting married or divorced, and changes in income that affect your Part B premium. Some events, like losing Medicaid, also may have access to. Contact Medicare to confirm whether your specific situation opens a Special Enrollment Period.

Will I owe a penalty if I delay Part B because I am still working?

No, as long as you request the delay in writing before your Initial Enrollment Period ends and you are covered by your employer's group health plan. You must have this coverage through your own employment or your spouse's current employment — retiree coverage does not count.