GLOSSARY · MEDICARE

Annual Enrollment Period (AEP)

October 15 – December 7 each year — change Medicare Advantage and Part D plans for next year.

Medicare 📋 Reviewed by InsureCo Editorial Team · Updated April 30, 2026
Quick definition: October 15 – December 7 each year — change Medicare Advantage and Part D plans for next year.

Full explanation

The Annual Enrollment Period (AEP), also called Annual Election Period or Open Enrollment, runs October 15 through December 7 every year. During AEP you can: switch from Original Medicare to Medicare Advantage; switch from Medicare Advantage back to Original Medicare; change MA plans; change Part D plans; enroll in Part D for the first time. Changes take effect January 1 of the next year. AEP is NOT the time to switch Medigap plans in most states — Medigap switching usually requires medical underwriting outside your initial 6-month Medigap Open Enrollment.

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