Deadlines that matter
Open enrollment 2026: the dates, the moves, and a 30-minute checklist
Short answer: Medicare’s Annual Enrollment Period runs October 15 through December 7, 2026, and every change you make takes effect January 1, 2027. It’s the one window each year when everyone can switch drug plans, switch Advantage plans, or move between Advantage and Original Medicare. Here’s what’s on the table, what isn’t, and how to handle the whole thing in one focused sitting.
Key takeaways
- The Annual Enrollment Period (AEP) runs October 15 to December 7, 2026; changes take effect January 1, 2027.
- During AEP anyone can switch Part D plans, switch Advantage plans, join or leave Advantage entirely.
- AEP does not guarantee you a Medigap plan; outside protected windows, Medigap can still require underwriting in most states.
- Your Annual Notice of Change arrives in September and tells you exactly what your current plan will cost and cover in 2027.
- A second window, the MA Open Enrollment Period, runs January 1 to March 31, 2027, but only for people already in an Advantage plan.
The windows, in order
| Window | Dates | Who it’s for | What you can do |
|---|---|---|---|
| Annual Notice of Change arrives | September 2026 | Everyone in an Advantage or Part D plan | Read what your plan changes on January 1 |
| Annual Enrollment Period (AEP) | October 15 – December 7, 2026 | Everyone with Medicare | Switch drug plans, switch Advantage plans, join or leave Advantage |
| Coverage takes effect | January 1, 2027 | Everyone who made a change | New plan, new ID cards, new rules |
| MA Open Enrollment Period | January 1 – March 31, 2027 | Only people already in an Advantage plan | One switch: to another Advantage plan or back to Original Medicare |
AEP and MA OEP dates are set in federal law and repeat annually.
The last-received application wins: if you submit a change and then change your mind before December 7, submit again and the newest choice takes effect. Nothing you do during AEP interrupts your current coverage before January 1.
What you can change during AEP
- Your Part D drug plan. The most valuable move for the most people. Formularies, deductibles (up to $615 in 2026, with 2027 amounts announced in the fall), and preferred pharmacies all shift each January, and the plan that was cheapest for your drug list last year frequently isn’t this year.
- Your Medicare Advantage plan. Swap to a different Advantage plan whose network still includes your doctors and whose formulary still includes your drugs.
- Your path. Leave Original Medicare for Advantage, or leave Advantage for Original Medicare plus a stand-alone drug plan. Path switches deserve the most homework, because one direction is much easier to reverse than the other.
What AEP doesn’t do
AEP does not create a right to buy a Medigap plan. If you leave Advantage for Original Medicare during AEP, your ability to get Medigap still depends on your state and your situation: a trial right, a guaranteed-issue event, a generous state, or, failing those, medical underwriting. The order of operations in our switching guide exists precisely for this move: get the Medigap approval first, then disenroll.
AEP also isn’t needed for Original Medicare itself: Parts A and B don’t change during this window, and people happy with their current setup are allowed to do exactly nothing, provided the September notice didn’t move anything against them. Verifying that is the point of the checklist.
The 30-minute checklist
- Minutes 0–5: find your Annual Notice of Change. It arrived in September, paper or electronic. Pull out three numbers for 2027: premium, drug deductible, out-of-pocket maximum. Circle anything that grew.
- Minutes 5–10: check your doctors. Call the office or check the plan’s 2027 directory for each doctor you actually see. Confirm the specific plan, not the insurer brand.
- Minutes 10–20: run your drug list. Enter every prescription and your preferred pharmacy into Medicare.gov’s plan finder. Sort by total annual cost, not premium. This step alone finds most of the money.
- Minutes 20–25: compare the top result to staying put. If staying costs within a small margin of the best alternative, inertia is fine this year. If the gap is hundreds of dollars, it isn’t.
- Minutes 25–30: act or file. Enroll in the better plan through the plan finder (the new enrollment automatically replaces the old plan), or write down "checked, staying" with the date. Future you will want the receipt.
If you only do one thing: run the drug list. Plan finder comparisons of total annual cost catch formulary changes, tier moves, and pharmacy-network shifts that no premium comparison will ever show you.
The AEP mistakes that fill January’s forums
- Letting the plan auto-renew unread. The plan you have on December 7 continues on January 1, with whatever new prices and networks September’s unread envelope disclosed.
- Shopping by premium. A $0 premium with the wrong formulary can cost more in one quarter than a $40 premium costs all year.
- Dropping Advantage before securing Medigap. Covered above; it’s the expensive version of doing things in the wrong order.
- Waiting for December. Phone lines, broker calendars, and plan-finder patience all degrade as the deadline approaches. The tool works the same on October 16, with none of the crowd.
Questions people also ask
When is Medicare open enrollment in 2026?
What can I change during the Annual Enrollment Period?
Does open enrollment let me buy a Medigap plan?
What happens if I do nothing during open enrollment?
When do 2027 Medicare costs come out?
Sources for this article
- Medicare.govMedicare Plan Finder: the official tool for the drug-list comparison at the heart of the checklist.
- Medicare.govWhen can I buy a Medigap policy: why AEP doesn’t create Medigap rights.
- CMS.gov2026 premiums and deductibles: the current-year figures referenced here; 2027 amounts arrive in the fall.
Figures checked against these sources in July 2026. We update within weeks when CMS publishes new amounts.