Medicare
Annual Enrollment Period (AEP)
The AEP is the primary annual opportunity for Medicare beneficiaries to change their Medicare Advantage or Part D drug plan, with changes taking effect January 1.
Last reviewed: May 2026 · Editorial methodology
Definition
The Annual Enrollment Period (AEP), also called the Fall Open Enrollment Period, runs October 15 through December 7 each year and is the primary window during which Medicare beneficiaries can make changes to their Medicare Advantage and Part D coverage. During AEP, beneficiaries may switch from one Medicare Advantage plan to another, switch from Medicare Advantage back to Original Medicare (with or without adding a stand-alone Part D plan), switch between stand-alone Part D plans, or add Part D coverage for the first time (though a late enrollment penalty may apply if they went without creditable coverage). All AEP elections take effect January 1 of the following year. AEP is distinct from the Medicare Advantage Open Enrollment Period (MA OEP), which runs January 1–March 31 and allows beneficiaries already enrolled in MA to make one plan change. It is also distinct from Special Enrollment Periods triggered by qualifying events. Beneficiaries should compare plans annually during AEP because formularies, premiums, networks, and extra benefits change year to year.
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Cover Forge USA Editorial Team
Editorial Lead
This article was researched and written by the Cover Forge USA editorial team against federal sources (NAIC, CMS, FEMA, DOL, SSA, state DOIs) and standard policy forms. Bylines organize content by topic — they do not assert individual licensure. See our editorial-policy for details.
Reviewed 2026-06-14
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