Medicare's Annual Enrollment Period runs October 15 through December 7, 2026, and any change you make takes effect January 1, 2027. During AEP you can switch Medicare Advantage plans, move between Medicare Advantage and Original Medicare, or change your Part D drug plan. The preparation that matters happens before October 15: read the Annual Notice of Change your plan mails by September 30, list your current doctors and prescriptions, and confirm both are still covered next year.
Preparing for Medicare's Annual Enrollment Period takes about an hour, and almost all of it happens before the window opens on October 15. Find the Annual Notice of Change your plan mails by September 30, write down every prescription and every doctor you see, and add up what this year actually cost you. Do that, and the decision itself takes fifteen minutes instead of a frantic afternoon on December 6.
Most people treat Medicare’s Annual Enrollment Period as a deadline. It is better understood as an audit. Your plan does not stay the same from year to year. Premiums move. Drug formularies drop medications and add others. Networks gain and lose providers. Copays shift by $10 here and $40 there. None of that requires your signature — it happens automatically on January 1 unless you look at it and decide otherwise.
Figures in this article reflect federal guidance published as of August 26, 2026 and apply nationwide. The 2027 Part B premium and deductible are typically announced in November. Plan-level premiums, formularies, and networks vary by county and post to Medicare Plan Finder on October 1. Confirm current amounts at medicare.gov or with a licensed broker before you enroll. Sources are listed at the end of this article.
When is Medicare’s Annual Enrollment Period?
The Annual Enrollment Period, usually shortened to AEP, runs from October 15 through December 7 every year, in every state. Coverage you choose during that window begins the following January 1. Here is the full calendar for the 2027 plan year.
| Date | What happens |
|---|---|
| By September 30, 2026 | Your plan mails your Annual Notice of Change, the document listing every 2027 change to your premium, copays, formulary, and network |
| October 1, 2026 | 2027 plan details go live on Medicare Plan Finder, and carriers may begin marketing next year's plans |
| October 15, 2026 | AEP opens, so you can enroll, switch, or drop |
| December 7, 2026 | AEP closes at 11:59 p.m. |
| January 1, 2027 | Your new coverage begins |
| January 1 – March 31, 2027 | Medicare Advantage Open Enrollment Period, a limited second chance described below |
If you submit more than one application during AEP, the last one filed before December 7 is the one that takes effect. That is useful if you change your mind, and it is also why an early decision is never a trap.
Why does AEP matter if you are happy with your plan?
Because “happy with my plan” describes the plan you had this year, and that is not automatically the plan you will have next year. Four things can change on January 1 without you lifting a finger.
- Your drugs. Part D and Medicare Advantage formularies are rebuilt annually. A medication on Tier 2 this year can move to Tier 4, require prior authorization, or leave the formulary entirely.
- Your doctors. Carriers and health systems renegotiate contracts every year. A provider who is in-network today may not be in January, and network changes are often the first thing people notice, usually too late.
- Your costs. Plan premiums, deductibles, specialist copays, and the in-network out-of-pocket maximum all reset annually.
- The plan itself. Plans are sometimes discontinued or pulled out of a county entirely. If that happens you will get a non-renewal notice and a Special Enrollment Period, but only if you open the mail.
What can, and cannot, be changed during AEP?
AEP covers Medicare Advantage and Part D. It does not cover everything people expect it to, and that is where most of the confusion lives, because “open enrollment” gets used for several different windows that follow different rules.
| What you want to do | Can you do it during AEP? |
|---|---|
| Switch from one Medicare Advantage plan to another | Yes |
| Switch from Original Medicare to Medicare Advantage | Yes |
| Drop Medicare Advantage and return to Original Medicare | Yes |
| Join, switch, or drop a standalone Part D drug plan | Yes |
| Buy or switch a Medigap policy | Not an AEP right — see below |
| Enroll in Medicare Part A or Part B for the first time | No — that is the Initial or General Enrollment Period |
The Medigap exception is the one that catches people. Medicare Supplement policies have no annual enrollment period at all. You can apply any time of year, but outside your one-time six-month Medigap Open Enrollment Period, most states allow carriers to medically underwrite you, meaning they can review your health history, charge you more, or decline you altogether.
This is one of the few areas where your state genuinely changes the answer. A handful of states grant additional guaranteed-issue rights through annual birthday-rule windows, anniversary windows, or continuous open enrollment. Most states grant none. The practical version: dropping Medicare Advantage during AEP is easy, and getting a Medigap policy to catch you on the other side may not be. If you are weighing that move, start the Medigap application before you cancel anything. Our breakdown of what Medicare supplement plans actually cover walks through the standardized plan letters, and our head-to-head comparison of Medicare Advantage and Medigap covers the trade-offs. That second article uses one state’s market for its cost examples, but the structural comparison holds anywhere.
How do you prepare for AEP?
Work through these in order. The first four steps happen before October 15, which is the whole point — by the time the window opens, you are comparing rather than gathering.
Find your Annual Notice of Change and actually read it
It arrives by September 30 in a plain envelope that looks like junk mail. Go straight to the comparison table showing this year's costs beside next year's. If any number moved meaningfully, that is your reason to shop.
Write down every prescription
Drug name, dosage, and how often you take it. Include the pharmacy you use, because network status affects your cost and preferred pharmacy tiers can swing a single copay considerably.
List your doctors and facilities
Primary care, every specialist, your preferred hospital, and any imaging or infusion center you use regularly. Do not rely on memory for the ones you see once a year.
Add up what you actually spent this year
Premiums, copays, drug costs, and dental and vision out-of-pocket. Total annual cost is the only fair way to compare plans. A plan with no premium that charges you $4,000 in copays is not cheaper than a $60-a-month plan that charges you $900.
Compare on October 1, decide by mid-November
Run your drug list through Medicare Plan Finder or have a broker do it. Verify every doctor directly with the plan or the practice, because online directories carry errors. Give yourself a buffer before December 7 for confirmations and callbacks.
Confirm, then keep the paperwork
Save your confirmation number. Your new card should arrive in December. Check in January that your first prescription fills at the price you expected, because that is when errors surface.
Most beneficiaries never compare plans during AEP, and many of them are fine. The ones who get hurt are almost always the ones who had a drug change tiers or a specialist leave the network, and who found out at the pharmacy counter in February, when the window to fix it had already closed.
What are the most common AEP mistakes?
Nearly every expensive AEP mistake comes from comparing the wrong thing, or from assuming last year’s answer still applies. These are the six worth guarding against.
A plan with no monthly premium is a starting point, not a total cost. Compare deductibles, copays, and the out-of-pocket maximum together.
Medicare Advantage and Part D plans are approved county by county. The plan a friend recommends may not exist where you live, and the same plan name can carry different networks and copays in a neighboring county.
If you split the year between two states or travel for months at a time, verify how your plan handles routine care outside its service area. Most HMOs cover emergency and urgent care only.
Physicians move between systems and networks. Verify each one individually, by name, every year.
Marketing volume during AEP is extraordinary. Advertised benefits are real for some plans in some counties. Confirm availability in your ZIP code before you act on anything.
Carrier call centers are at peak volume, and verification takes days you may not have left.
What if you miss December 7?
You have fewer options after December 7, but not zero. Three doors stay open, and each one has conditions attached.
- The Medicare Advantage Open Enrollment Period, January 1 through March 31, 2027. If you are enrolled in a Medicare Advantage plan, you get one switch: to a different Medicare Advantage plan, or back to Original Medicare with a standalone Part D plan. This window does not apply if you are on Original Medicare.
- Special Enrollment Periods. Moving out of your plan’s service area, losing employer coverage, entering or leaving a nursing facility, qualifying for Extra Help or Medicaid, or your plan leaving your county can each open one.
- The 5-star Special Enrollment Period. If a 5-star Medicare Advantage or Part D plan is available where you live, you can move to it once between December 8 and November 30.
Absent one of those, the coverage you have on January 1 is your coverage for the year. That is the real cost of letting the window pass.
Ready to make this year’s Medicare decision the easy one?
Knowing the AEP calendar is the education. Running your specific drug list against every plan available in your ZIP code, and verifying that your actual doctors are actually in-network, is the work.
That is what a consultation does. We start with the list you built in steps two and three, and we finish with a side-by-side of total expected annual cost, not just premiums. There is no pitch for a particular carrier, just your numbers. If your current plan wins, that is a good outcome too, and now you know it rather than assume it.
At Duncan Market Insurance, Carolyn Duncan has spent more than 20 years in the insurance industry and works today as an independent broker licensed in Florida. We are based in St. Augustine and serve clients across Northeast Florida, and because consultations happen by phone or video, sitting down together is simple wherever you are in the state. If you are not sure how to evaluate the person helping you with a decision this size, here is what to look for in an insurance broker. Our Medicare services page covers the full range of what we help with, and the rest of our Education Center goes deeper on the individual pieces.
Book a consultation → · Call 904-217-8368
Sources
- Joining a Plan, Medicare.gov
- Understanding Medicare Advantage Plans, Medicare.gov
- Costs for Medicare Drug Coverage, Medicare.gov
- Medigap (Medicare Supplement Insurance), Medicare.gov
- Medicare Advantage and Part D fact sheets, Centers for Medicare & Medicaid Services
Key takeaways
Frequently asked questions
When is Medicare's Annual Enrollment Period in 2026?
October 15 through December 7, 2026, in every state. Coverage you choose during this window begins January 1, 2027. The dates are the same every year.
Do I have to do anything during AEP if I like my current plan?
No, most plans renew automatically. But you should still read your Annual Notice of Change, because your premium, copays, drug formulary, and provider network can all change on January 1 without your involvement.
What is an Annual Notice of Change (ANOC)?
A document your Medicare Advantage or Part D plan must send by September 30 each year, listing every change to your coverage for the coming year — premium, deductible, copays, formulary tiers, and network. It is the fastest way to tell whether you need to shop.
Can I switch Medicare Supplement (Medigap) plans during AEP?
Not as an AEP right. Medigap has no annual enrollment period. You can apply year-round, but outside your one-time six-month Medigap Open Enrollment Period, most states allow insurers to medically underwrite your application. A few states offer additional guaranteed-issue windows, so check your state's rules before you assume you can switch.
What happens if I miss the December 7 deadline?
If you are in a Medicare Advantage plan, you can make one change during the Medicare Advantage Open Enrollment Period, January 1 through March 31. Otherwise you would need a Special Enrollment Period, triggered by things like moving, losing employer coverage, or qualifying for Extra Help.
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