Medicare Timing
Medicare Enrollment Periods
When you can enroll in Medicare coverage, or change coverage you already have, depends on which enrollment period you are in. Missing one can mean waiting months for another chance, and in some cases paying a penalty for as long as you have coverage.
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The enrollment periods
Initial Enrollment Period
IEP7 months around your 65th birthday
Begins 3 months before the month you turn 65, includes that month, and ends 3 months after. This is when most people first enroll, and enrolling early in the window generally means coverage starts sooner.
Annual Enrollment Period
AEP15 October to 7 December
Each autumn you can join, switch, or drop a Medicare Advantage or Part D plan. Changes made during this window generally take effect on 1 January.
Read more about the Annual Enrollment PeriodMedicare Advantage Open Enrollment
MA OEP1 January to 31 March
If you are already in a Medicare Advantage plan you can switch to a different one, or return to Original Medicare, once during this window. It is not available to people who are in Original Medicare on 1 January.
Read more about the Medicare Advantage Open EnrollmentGeneral Enrollment Period
GEP1 January to 31 March
For people who did not sign up for Part B when first eligible and do not qualify for a Special Enrollment Period. A late enrollment penalty may apply.
Medigap Open Enrollment Period
Medigap OEP6 months from Part B enrollment at 65
Begins the month you are both 65 or older and enrolled in Part B. During it you can buy any Medigap policy sold in your state regardless of your health. It does not repeat.
Special Enrollment Period
SEPWhen your circumstances change
Certain life events, such as moving or losing other coverage, can open a window to make a change outside the usual periods. How long it lasts depends on the event.
Read more about the Special Enrollment PeriodWhy the timing matters
Delaying coverage past the point you were first eligible can result in a late enrollment penalty. For Part B, an amount is added to your premium for each full 12 month period you could have had it and did not, and it generally continues for as long as you have Part B.
Part D works similarly. Going 63 days or more in a row without Part D or other creditable prescription drug coverage after your Initial Enrollment Period can result in an amount being added to your premium for as long as you have coverage.
Some situations avoid a penalty entirely, such as having creditable coverage through an employer. Whether that applies to you is worth confirming rather than assuming.