If you are eligible for Medicare but not currently receiving Social Security retirement benefits or Railroad Retirement benefits, there are three different time periods during which you can enroll in Medicare Parts A and B.

  1. Initial Enrollment Period (IEP). You can enroll in Medicare at anytime during this seven-month period, which includes the three months before, the month of, and the three months following your 65th birthday. The date when your Medicare coverage begins depends on when you sign up.
    • If you enroll during the first three months of your IEP, coverage begins the month in which you first become eligible for Medicare.
    • If you enroll during the fourth through seventh months of your IEP, coverage begins the month following the month of enrollment.

For example, let’s say you turn 65 in June. Use the following chart to determine when you can enroll in Medicare and when your coverage would start.

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You can enroll anytime in: Your coverage starts:
March June 1st
April June 1st
May June 1st
June July 1st
July August 1st
August September 1st
September October 1st
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It is important to note that if your birthday falls on the first of the month, your IEP is the seven months surrounding the month prior to the month of your birth. For example, let’s say you turn 65 on June 1. Your IEP runs from February 1 to August 31.

2. Part B Special Enrollment Period (SEP) for job-based insurance. SEPs are periods of time outside of normal enrollment periods, triggered by specific circumstances. This Part B SEP lets you delay enrollment in Part B without penalty if you were covered by insurance based on your or your spouse’s current work (job-based insurance) when you first become eligible for Medicare. You can enroll in Medicare without penalty for up to eight months after you lose your group health coverage or you (or your spouse) stop working, whichever comes first. Medicare coverage begins the first month after you enroll. For example, if you retire and sign up for Medicare in February, your coverage will begin March 1. To avoid a gap in coverage, enroll in Medicare the month before your job-based insurance will end.

There are also Special Enrollment Periods for some less common situations, such as if you could not enroll in Medicare on time because you live in an area that was affected by a government-declared state-of-emergency or disaster.  

3. General Enrollment Period (GEP). If you did not enroll in Medicare when you originally became eligible for it (either during your IEP or an SEP), you can sign up during the GEP. The GEP takes place January 1 through March 31 each year, with coverage starting the first of the month after the month you enroll. You may incur a Part B late enrollment penalty and face gaps in coverage if you sign up during the GEP.