When is the Medicare Annual Enrollment Period?
The Medicare Annual Enrollment Period (AEP) runs October 15 through December 7 every year, including 2026. Changes you make take effect January 1. During AEP you can join, drop, or switch Medicare Advantage and Part D drug plans for the coming year.
Last reviewed August 17, 2026 · Published August 17, 2026 · Mere Benefits Data Desk
AEP is not the window for signing up for Medicare itself. First-time enrollment in Parts A and B happens during your 7-month Initial Enrollment Period around your 65th birthday, the January 1 to March 31 General Enrollment Period, or a Special Enrollment Period. AEP is the annual window for changing how you receive your benefits: your Medicare Advantage or Part D drug plan choices for the following year.
The Medicare enrollment calendar
| Enrollment period | Dates | What you can do |
|---|---|---|
| Annual Enrollment Period (AEP) | Oct 15 to Dec 7 | Join, switch, or drop Medicare Advantage or Part D plans; changes start Jan 1 |
| Initial Enrollment Period (IEP) | 7 months around your 65th birthday month | First-time enrollment in Parts A, B, and a plan |
| General Enrollment Period (GEP) | Jan 1 to Mar 31 | Enroll in Part B if you missed your IEP; coverage starts the month after you enroll |
| MA Open Enrollment Period | Jan 1 to Mar 31 | Already in Medicare Advantage? Make one switch to another MA plan or back to Original Medicare |
| Special Enrollment Periods (SEPs) | Event-driven | Example: 8 months to enroll in Part B after losing employer coverage; 2 months for a plan change |
What to actually do each fall
Every September, your current plan mails an Annual Notice of Change showing next year’s premium, deductible, drug formulary, and provider network. Plans change more than most people expect. For 2026 plan choices, the numbers worth checking against each plan include the $2,100 annual out-of-pocket cap on Part D drug costs and the maximum standard Part D deductible of $615, along with whether your medications stay on the formulary and your doctors stay in network.
Example: if your drug plan raises its deductible to the full $615 for 2026 and moves one of your medications to a higher tier, a 20-minute comparison during AEP may save you hundreds of dollars next year. Miss December 7 and you are generally locked in for the year unless a Special Enrollment Period applies to you.
One nuance: Medigap (Medicare Supplement) policies do not follow AEP. In most states you can apply for Medigap any time of year, but outside your one-time 6-month Medigap open enrollment window after starting Part B, insurers may use medical underwriting and can decline you, depending on your state’s rules.
Here’s the mistake I see every October: ignoring the Annual Notice of Change because “nothing ever changes.” The years it does change are exactly the years that letter pays for itself.
Sources
- Medicare.gov — Joining a plan (enrollment periods) (2026-08-17)
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