Initial Enrollment Period (IEP)
If you are turning 65, your IEP is typically a 7-month window: 3 months before your birthday month, your birthday month, and 3 months after. Enrolling earlier in the window can reduce the chance of a coverage gap.
Annual Enrollment Period (AEP)
AEP runs October 15 – December 7 each year. During AEP you can join, switch, or drop Medicare Advantage or Part D coverage, with changes usually effective January 1.
Medicare Advantage Open Enrollment Period
If you start the year in a Medicare Advantage plan, you may have a window from January 1 – March 31 to switch to a different Advantage plan or return to Original Medicare (and join a Part D plan).
Special Enrollment Periods
Certain events — moving, losing employer coverage, changes in Medicaid, and others — can create an SEP. Rules and deadlines are event-specific. Document the event and verify the deadline before you act.