Medicare Glossary

Definitions for common Medicare terms

Medicare open enrollment

DEFINITION: Medicare open enrollment – also known as the annual election period or annual coordinated election period  – refers to the annual period (October 15 through December 7) during which Medicare plan enrollees can reevaluate their coverage — whether it’s Original Medicare with supplemental drug coverage, or Medicare Advantage — and make changes if they want to do so.

During Medicare open enrollment, a beneficiary can:

But the annual open enrollment does not apply to Medigap plans, which are only guaranteed-issue in most states during a beneficiary’s initial enrollment period, and during limited special enrollment periods.

Medicare open enrollment begins on October 15 and ends on December 7, with changes effective on January 1.

Starting in 2019, there’s another open enrollment period that only applies to people who have coverage under Medicare Advantage plans. The Medicare Advantage open enrollment period runs from January 1 to March 31, and allows Medicare Advantage enrollees to either switch to Original Medicare (plus a Part D plan if they want one) or switch to a different Medicare Advantage plan. Enrollees are only allowed to make one change during this three-month window — they can’t switch to a Medicare Advanage plan in February and then switch to a different one in March, for example.