Definition. The yearly window, October 15 to December 7, when anyone with Medicare can change Medicare Advantage or Part D coverage for the next year. Medicare.gov calls it the Open Enrollment Period.
What it means
The Annual Enrollment Period (AEP) is the main time each year to review your coverage. Between October 15 and December 7 you can:
- Switch from Original Medicare to a Medicare Advantage plan, or from Medicare Advantage back to Original Medicare.
- Switch from one Medicare Advantage plan to another.
- Join, switch or drop a Part D drug plan.
Your last choice before December 7 counts, and it starts January 1. If you do nothing, you usually stay in your current plan as it changes for the new year, so read your plan's Annual Notice of Change first. Medigap isn't tied to the AEP: you can apply for a Medigap policy any time, though outside your protected windows the company can review your health.
In Oregon
For 2027 coverage, CMS lists 61 Medicare Advantage plans open to all beneficiaries in Oregon and 8 standalone Part D plans, but choices depend on your county: there is no Medicare Advantage plan open to everyone in Grant, Harney, Lake, Umatilla and Union counties, and only a special needs plan in Curry County. Check your county on the county pages. Some companies are also stopping Medicare Advantage plans in parts of Oregon for 2027; if your plan is ending, you get a non-renewal letter and more time to choose (see plans ending in 2027).
Sources
- Medicare.gov — Joining a health or drug plan
- Medicare.gov — Understanding Medicare Advantage & drug plan enrollment periods (PDF)
- Medicare.gov — Your yearly Medicare review (PDF)
- eCFR — 42 CFR 422.62, election of coverage under an MA plan
- CMS — 2027 Medicare Advantage and Part D Landscape files (Oregon plan counts)
Frequently asked questions
Can I change my Medigap plan during the AEP?
The AEP doesn't apply to Medigap. You can apply for a different Medigap policy any time, but outside a guaranteed issue window or Oregon's birthday rule window the company may review your health and can turn you down.
When does a change I make during the AEP start?
January 1 of the next year. If you make more than one change before December 7, the last one counts.
Medicare in your Oregon county
Plans, local agents and help, county by county: Multnomah · Washington · Clackamas · Lane · Marion · Jackson · Deschutes · Linn · Douglas · Yamhill · Benton · Polk · Josephine · Umatilla · Klamath · Coos · Columbia · Lincoln · Clatsop · Malheur · All 36 counties →
