Every fall, Medicare beneficiaries get one guaranteed opportunity to review and change their coverage without a qualifying life event: the Annual Enrollment Period, or AEP. For AEP 2026, that window runs October 15 through December 7, 2026, with any changes taking effect January 1, 2027 — what’s often called Plan Year 2027 coverage.
If you’re already enrolled in Medicare, understanding how to use this window well can mean the difference between a plan that quietly cost you more than it should have and one that actually fits your needs, doctors, and prescriptions for the year ahead.
What AEP Actually Is
AEP is specifically for people already enrolled in Medicare who want to make a change to their existing coverage. It’s different from the Initial Enrollment Period (the window around your 65th birthday when you first sign up) — AEP exists every single year, giving you a recurring checkpoint to reassess your coverage rather than locking you into a decision made years ago.
During AEP, you can:
- Switch from one Medicare Advantage plan to another
- Switch from one Part D prescription drug plan to another
- Switch from Original Medicare to a Medicare Advantage plan
- Switch from a Medicare Advantage plan back to Original Medicare
- Enroll in Part D for the first time, if you didn’t previously have creditable drug coverage (though a late enrollment penalty may still apply if you had a coverage gap)
What AEP Does Not Cover
AEP is not a catch-all enrollment window. A few important limits:
- Medigap enrollment isn’t tied to AEP. If you switch from Medicare Advantage to Original Medicare during AEP and want to add a Medigap policy, that’s a separate application, and outside your one-time Medigap Open Enrollment Period, insurers in most states can use medical underwriting to deny coverage or charge more.
- It’s not for first-time Medicare enrollment. If you’re not yet on Medicare at all, you’re working with your Initial Enrollment Period, not AEP — see our full enrollment guide for that timeline.
- Changes take effect January 1, not immediately. Whatever you choose during AEP 2026 doesn’t start until January 1, 2027 — you’re still covered under your current plan through the end of the current plan year.
How to Prepare Before AEP Opens
The weeks before October 15 are the best time to do your homework, not the weeks during AEP itself, when you’re comparing plans under time pressure. A few things worth doing in advance:
- Read your plan’s Annual Notice of Change (ANOC). Your current Medicare Advantage or Part D plan sends this document every September, detailing what’s changing for the next plan year — premiums, copays, and formulary updates. This is often the single most useful document for deciding whether to shop around.
- List your current medications and doctors. Having this on hand makes comparing plans dramatically faster once AEP opens, since formulary and network status are the two details that matter most for most people.
- Decide what you’re optimizing for. Lower premium, broader provider network, better drug coverage, or extra benefits like dental and vision — knowing your priority before you start comparing plans keeps the process focused.
Common AEP Mistakes
A few patterns come up again and again during AEP season:
- Assuming last year’s plan is still the best option without checking the ANOC — formularies and networks change every year, even for plans you don’t switch.
- Comparing only the monthly premium, without factoring in the plan’s out-of-pocket maximum, copays, or how your specific prescriptions are covered.
- Waiting until the last few days of AEP, which leaves little time to research or get help if you decide you want a second opinion.
- Not verifying provider networks directly — a plan’s marketing materials aren’t always a reliable source for whether your specific doctor is currently in-network.
For the fuller list of Medicare mistakes worth avoiding year-round, not just during AEP, see our Top 7 Medicare Mistakes guide.
Why Working With a Licensed Agent Helps During AEP
AEP compresses a lot of decision-making into a 7-week window, and plan options can genuinely be complex to compare on your own — especially if you’re weighing Medicare Advantage against Medigap, or comparing multiple Part D formularies against a specific medication list. A licensed insurance agent can walk through your specific doctors, prescriptions, and budget, and help you compare options without the pressure of a sales pitch. This kind of review costs you nothing directly — agents are generally compensated by the insurance carriers, not by you.
If you’re trying to decide whether Medicare Advantage or Medigap fits your situation better before AEP opens, our coverage options guide walks through the full comparison, including how to estimate total annual cost rather than comparing premiums alone.
Ready to Review Your Coverage?
Kayla Price is a licensed insurance agent (NPN 18530055) offering free, no-pressure AEP reviews. Call (866) 648-1578 to get started before AEP 2026 opens on October 15.