The Medicare Annual Enrollment Period, often called AEP or Medicare Open Enrollment, runs from October 15 to December 7, 2026. Every person with Medicare, not just people signing up for the first time, can use this window to switch Medicare Advantage plans, move between Original Medicare and Medicare Advantage, or change Part D drug coverage. Any change you make takes effect January 1, 2027. Miss the deadline and you are generally locked into your current coverage for the rest of 2027, with only a few narrow exceptions. Here is exactly what the AEP covers, what it does not, and how to use it before December 7.
Medicare AEP 2026 Key Dates
| Date | What Happens |
|---|
| October 1, 2026 | Plans can start marketing 2027 coverage details |
| October 15, 2026 | AEP officially opens, you can submit changes |
| December 7, 2026 | AEP closes, this is the hard deadline |
| January 1, 2027 | All AEP changes take effect |
The window is exactly the same every year: October 15 through December 7. It does not shift based on your birthday, your state, or your current plan. If you take no action during AEP, your existing coverage typically continues into 2027 automatically, though your plan's costs, drug list, and provider network can still change year to year even if you do nothing.
What You Can Change During AEP
The Annual Enrollment Period is the broadest of Medicare's enrollment windows. During AEP you can:
- Switch from Original Medicare to a Medicare Advantage plan
- Switch from Medicare Advantage back to Original Medicare
- Switch from one Medicare Advantage plan to a different one
- Join a Part D prescription drug plan for the first time
- Switch from one Part D plan to another
- Drop Part D coverage entirely
If you switch from Medicare Advantage back to Original Medicare during AEP, you can also enroll in a Part D plan at the same time without a late penalty. Keep in mind that returning to Original Medicare does not guarantee you can buy a Medigap supplement policy without medical underwriting. Medigap guaranteed-issue rights are separate from Medicare's enrollment periods and vary by state, so check your state's rules before assuming you can add a Medigap plan penalty-free.
What AEP Does NOT Cover
AEP is not the window to sign up for Medicare for the first time if you are not already enrolled in Part A or Part B. First-time enrollment runs through your Initial Enrollment Period, the 7-month window centered on your 65th birthday. If you are approaching 65 or trying to figure out when your personal enrollment window opens, see our guide on the Medicare Initial Enrollment Period.
AEP also is not the right window if you are enrolling because of a specific life event, like losing employer coverage, moving out of your plan's service area, or losing Medicaid. Those situations are covered by a Special Enrollment Period, which can open at any time of year depending on the trigger. If one of those situations applies to you, see our guide on Medicare Special Enrollment Periods and qualifying events rather than waiting for AEP.
Finally, AEP does not let you enroll in Part A or Part B for the first time if you missed your Initial Enrollment Period and do not qualify for a SEP. That situation falls under the General Enrollment Period, January 1 to March 31, with coverage starting the month after you enroll and a possible late enrollment penalty attached.
AEP vs. Medicare Advantage Open Enrollment Period (MA OEP)
These two windows get confused constantly because they both happen near the start of the year and both let you change Medicare Advantage coverage. They are not the same thing.
| AEP | MA OEP |
|---|
| Dates | October 15 to December 7 | January 1 to March 31 |
| Who can use it | Anyone with Medicare | Only people already enrolled in a Medicare Advantage plan |
| Number of changes allowed | Unlimited during the window | One change |
| What you can do | Switch between Original Medicare, Medicare Advantage, and Part D plans | Switch to a different Medicare Advantage plan, or drop Medicare Advantage and return to Original Medicare with a Part D plan |
| Can you join Part D from Original Medicare? | Yes | No |
The Medicare Advantage Open Enrollment Period functions as a one-time do-over for people who picked a Medicare Advantage plan during AEP and realize by February or March that it is not working for them. It does not let you shop across every plan type the way AEP does. If you have Original Medicare and want to add or change a Part D plan outside of AEP, MA OEP will not help you, since it is limited strictly to current Medicare Advantage enrollees.
Why Reviewing Your Plan Every AEP Matters
Medicare Advantage and Part D plans are allowed to change their premiums, deductibles, copays, drug formularies, and provider networks every year. A plan that worked well for you in 2026 can look very different in 2027. Common year-over-year changes include:
- A drug moving to a higher cost tier or being dropped from the formulary
- Your doctor or specialist leaving the plan's network
- Premium or deductible increases
- Changes to out-of-pocket maximums for Medicare Advantage
- New or discontinued extra benefits, like dental, vision, or transportation coverage
Every fall, plans mail an Annual Notice of Change (ANOC) that spells out what is different for the coming year. Reading that notice before AEP opens gives you time to compare alternatives rather than scrambling in the final days before December 7.
How to Compare and Switch Plans During AEP
- Read your Annual Notice of Change. It arrives by late September and lists exactly what is changing about your current plan for 2027.
- List your medications and doctors. You will need this to check that any new plan you consider covers your prescriptions and keeps your providers in network.
- Use Medicare's Plan Finder at Medicare.gov. Enter your ZIP code, drugs, and pharmacy preference to compare Medicare Advantage and Part D plans side by side, including estimated total annual cost.
- Call 1-800-MEDICARE or your State Health Insurance Assistance Program (SHIP) if you want free, unbiased help. SHIP counselors do not sell insurance and can walk through your options with you at no cost.
- Enroll before December 7. You can enroll online through Medicare.gov, by calling the plan directly, by calling 1-800-MEDICARE, or through a licensed agent. If you make more than one change during AEP, only the last one you submit before the deadline takes effect.
- Confirm your new coverage. Your new plan should send an enrollment confirmation and a new member ID card before January 1, 2027.
Frequently Asked Questions
When does Medicare AEP start and end in 2026?
Medicare's Annual Enrollment Period runs from October 15, 2026, through December 7, 2026. Coverage changes made during this window take effect January 1, 2027.
Can I switch Medicare plans outside of AEP?
Generally no, unless you qualify for a Special Enrollment Period due to a specific event like moving, losing employer coverage, or losing Medicaid, or unless you are using the Medicare Advantage Open Enrollment Period from January 1 to March 31 and are already enrolled in a Medicare Advantage plan.
What happens if I do nothing during AEP?
If you take no action, your current Medicare Advantage or Part D plan typically continues automatically into 2027. However, your plan's premiums, formulary, and network can change even if you stay enrolled, so it is worth reviewing your Annual Notice of Change before assuming your coverage stays the same.
Is AEP the same as the Medicare Advantage Open Enrollment Period?
No. AEP runs October 15 to December 7 and is open to anyone with Medicare, letting you make unlimited changes across Original Medicare, Medicare Advantage, and Part D. The Medicare Advantage Open Enrollment Period runs January 1 to March 31, is limited to people already in a Medicare Advantage plan, and allows only one change.
Can I enroll in Medicare for the first time during AEP?
Not if you have never had Part A or Part B before. First-time enrollment happens during your Initial Enrollment Period, the 7-month window around your 65th birthday. AEP is only for changing coverage you already have.
Will I pay a penalty if I miss the AEP deadline?
Missing AEP itself does not create a late enrollment penalty, since you likely already have Part B and possibly Part D. But if you go 63 or more days without creditable drug coverage and then wait to join a Part D plan outside a qualifying window, you can face a permanent Part D late enrollment penalty when you eventually do enroll.
Does AEP affect Medigap supplement plans?
AEP itself does not create special rights to buy a Medigap policy. Medigap guaranteed-issue periods are separate and tied to specific events, like first joining Original Medicare or losing Medicare Advantage coverage, and rules vary significantly by state.
