Medicare’s Annual Election Period runs October 15 through December 7 and lets you join, switch, or drop Advantage and Part D plans for the new year. A separate Medicare Advantage Open Enrollment Period, January 1 through March 31, gives Advantage enrollees one chance to change. Knowing which window you’re in determines what changes you’re actually allowed to make.
The Annual Election Period — Oct 15 to Dec 7 — is Medicare’s big shopping season, open to everyone on Medicare. During AEP you can move between Original Medicare and Medicare Advantage in either direction, switch from one Advantage plan to another, and join, drop, or change Part D drug plans. Whatever you choose takes effect January 1. Before the window opens, your current plan sends a notice describing what’s changing next year — premiums, copays, networks, and drug lists all move annually, which is exactly why this window exists.
The Medicare Advantage Open Enrollment Period — Jan 1 to Mar 31 — is narrower and often misunderstood. It’s only for people already enrolled in a Medicare Advantage plan, and it allows exactly one change: switch to a different Advantage plan, or drop Advantage and return to Original Medicare (adding a Part D plan if you do). It is not a second chance for everyone; if you’re on Original Medicare, this window doesn’t let you make changes. Think of it as a safety valve — if your January copays or network turn out different than you expected, you have one do-over.
Treat AEP as your planned annual checkup and OEP as the emergency exit. Say you kept your Advantage plan through the fall, then discovered in January that your cardiologist left the network. That’s what OEP is for — one clean switch to a plan that still includes your doctor. But relying on OEP as a strategy is risky: it can’t help people on Original Medicare, it can’t fix a standalone drug plan choice, and it only comes with one move. The better habit is a real comparison every fall, even if you end up keeping what you have. Our annual review article explains why.
What should the fall checkup actually cover? Four things. Read the change notice your plan sends — it tells you next year’s premiums, copays, and benefit changes in plain terms. Re-verify your doctors, because networks are redrawn annually and a doctor who was in network this year isn’t guaranteed to be next year. Re-run your medications against next year’s formulary, since drugs move tiers and coverage rules change. And compare your plan’s next-year version against what else is available — not because switching is always right, but because the comparison is free and skipping it is how people drift into plans that stopped fitting years ago.
Outside both windows, changes generally require a Special Enrollment Period triggered by events like moving or losing coverage — see our special enrollment overview. And remember the numbers that frame every comparison in 2026: the Part D out-of-pocket drug cap of $2,100 a year and the Medicare Advantage in-network out-of-pocket cap of $9,250 both shape what a “bad year” could cost you under each plan.
Two cautions as the windows approach. First, marketing season peaks during AEP — expect a flood of mailers and ads, and remember that “new benefits in your area” is an invitation to compare, not proof that switching helps you. Second, don’t confuse doing nothing with staying the same: your plan changes every January whether you act or not, so “keeping my plan” still deserves the fall checkup. The people who come out ahead each year aren’t the ones who switch most — they’re the ones who checked.
If any of this feels like alphabet soup, that’s normal — it is alphabet soup. Our Medicare page lays the windows out visually, and a licensed advisor can tell you in one call which window applies to you and what your best move is: 561-339-0727, free.
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