Medicare AEP for 2027 coverage: the dates, what you can change, and the one thing it does not cover
The Annual Enrollment Period runs October 15 through December 7, 2026, and changes take effect January 1, 2027. Most people confuse it with the two other windows that follow, and one of those confusions costs money.
The short answer
Medicare's Annual Enrollment Period runs October 15 through December 7, 2026, for coverage that starts January 1, 2027. During it you can switch between Original Medicare and Medicare Advantage, change Medicare Advantage plans, or add, change, or drop a Part D drug plan. It does not give you a right to buy a Medigap policy without underwriting.
- Dates: October 15 through December 7, 2026. Changes take effect January 1, 2027.
- What you can change: Medicare Advantage enrollment, Medicare Advantage plan choice, and Part D coverage.
- What it does not do: AEP does not create a guaranteed-issue right to buy Medigap. Medigap runs on its own rules.
- Second window: Medicare Advantage Open Enrollment runs January 1 through March 31, 2027, and allows one change.
Applies to anyone already enrolled in Medicare who wants to change health or drug coverage for 2027. If you are turning 65, your Initial Enrollment Period is a separate seven-month window around your birthday month and is not tied to these dates.
When is Medicare’s Annual Enrollment Period for 2027 coverage?
October 15 through December 7, 2026. Anything you change during that window takes effect January 1, 2027.
The dates do not move. They are the same every year, which is worth knowing because the advertising around them gets louder each October and some of it implies urgency that is not real until December approaches.
If you are happy with your plan and nothing in it changed for 2027, you do not have to do anything. Your coverage renews on its own. The question is whether something changed, and the only way to know is to read the Annual Notice of Change your plan mailed by September 30.
What can you actually change during AEP?
Three things, and they cover most of what people want.
- Move from Original Medicare to a Medicare Advantage plan, or from Medicare Advantage back to Original Medicare.
- Switch from one Medicare Advantage plan to another.
- Add a Part D prescription drug plan, switch to a different one, or drop drug coverage entirely.
You do not need to cancel your old plan. Enrolling in a new one ends the previous coverage on December 31 automatically. Enrolling twice by mistake is a more common problem than enrolling late.
What does AEP not cover?
Medigap. This is the single most expensive misunderstanding in Medicare, and it is the reason people search for a “Medicare supplement annual enrollment period” that does not exist.
Medigap policies run on their own rules. Your guaranteed-issue window is the six months that begin when your Part B coverage starts. During that window an insurer cannot turn you down or charge you more because of your health. Once it closes, most states allow medical underwriting, which means you can be declined.
So you can leave Medicare Advantage during AEP and return to Original Medicare. Whether you can buy a Medigap policy to go with it is a separate question, answered by your state’s rules and your health history. Guaranteed-issue rights and underwriting vary by state.
How is the January window different?
Medicare Advantage Open Enrollment runs January 1 through March 31 and is narrower in every way. It is only for people already enrolled in a Medicare Advantage plan, and it allows exactly one change.
| Annual Enrollment Period | Medicare Advantage Open Enrollment | |
|---|---|---|
| Dates | October 15 to December 7 | January 1 to March 31 |
| Who it is for | Anyone with Medicare | Only current Medicare Advantage enrollees |
| Changes allowed | Unlimited until the deadline | One change |
| Join Medicare Advantage from Original Medicare | Yes | No |
| Switch Medicare Advantage plans | Yes | Yes |
| Return to Original Medicare | Yes | Yes |
| Change a standalone Part D plan | Yes | Only when leaving Medicare Advantage |
| Coverage starts | January 1 | First of the following month |
Treat January as a correction window, not a planning window. It exists so people who discover in the first weeks of the year that their new plan does not work are not trapped until the following December.
What should you check before December 7?
Start with the document your plan already sent you rather than with plan shopping. The Annual Notice of Change lists your 2026 and 2027 costs side by side, and it is the fastest way to see whether anything actually moved.
Four checks before the deadline
- Read the cost comparison table in your Annual Notice of Change. Premium, deductible, and cost sharing are shown for both years.
- Confirm every medication you take is still on the formulary, at what tier, and whether prior authorization or a quantity limit now applies.
- Confirm your doctors and hospital are still in network for 2027. Networks change even when premiums do not.
- Compare the estimated annual total, not the monthly premium, using your real drug list at Medicare.gov.
For 2027 there is one more reason to look. The federal subsidy that held down standalone drug plan premiums ended after 2026, so many Part D plans are priced differently than they were last year. We covered what changed in why your 2027 Part D premium is going up.
What if you miss December 7?
You generally wait. Your plan renews and you are in it for the calendar year, with the narrow January exception above if you are in a Medicare Advantage plan.
Special enrollment periods exist for specific circumstances: moving out of your plan’s service area, losing employer coverage, your plan leaving Medicare or exiting your county, entering or leaving a nursing facility, or qualifying for Extra Help. Each has its own timing rules, usually measured in days from the triggering event.
If your plan is being discontinued, do not simply take whatever replacement the carrier assigns. A termination can open a guaranteed-issue path to Medigap that is closed the rest of the year, and defaulting into another Medicare Advantage plan gives that up without anyone telling you.
Does any of this apply if you are turning 65?
Not directly. Your Initial Enrollment Period is a seven-month window: the three months before your birthday month, that month, and the three months after. It is tied to your birthday, not to the calendar.
The overlap matters only in one way. If your Initial Enrollment Period happens to fall in the autumn, you may be choosing your first plan while AEP advertising is at full volume. The rules that apply to you are the ones for your own window.
One date does carry over. Your Medigap open enrollment is the six months beginning when Part B starts, and during it no insurer can decline you for health reasons. That window does not repeat.
Questions people ask
Is there a Medicare supplement annual enrollment period?
No. Medigap does not run on the AEP calendar. Your guaranteed-issue window is the six months beginning when your Part B starts, plus specific qualifying events. Outside those, most states allow medical underwriting.
What happens if I do nothing by December 7?
Your current plan renews automatically with its 2027 premium, formulary, and network. You are generally locked in for the calendar year unless you qualify for a special enrollment period.
Can I switch Medicare Advantage plans in January?
Once. Medicare Advantage Open Enrollment runs January 1 through March 31 and allows one change: switch to a different Medicare Advantage plan, or return to Original Medicare and add a Part D plan.
My plan is leaving my area. Do I have to wait for AEP?
No. A plan termination triggers a special enrollment period, and it can also trigger a guaranteed-issue right to buy certain Medigap policies without underwriting, generally within 63 days.
Does my Part D late enrollment penalty go away if I switch plans?
No. The penalty is 1 percent of the national base beneficiary premium for each month you went without creditable drug coverage, and it follows you between plans.
Sources
- CMS, Medicare Open Enrollment Partner Resources, accessed September 17, 2026
- Medicare.gov, Find health and drug plans, accessed September 17, 2026
- CMS, Medicare Part D 2027 National Average Monthly Bid Amount Information, July 28, 2026
Not sure whether your 2027 plan still fits?
Send your medication list and the doctors you want to keep. A licensed advisor will compare your options before the December 7 deadline and reply within one business day. Free, no obligation.
Review my optionsCall or text (773) 657-9140Smart Insurance Agents LLC is an independent, licensed insurance agency and is not connected with or endorsed by the U.S. government or the federal Medicare program. We do not offer every plan available in your area. Please contact Medicare.gov, 1-800-MEDICARE, or your local State Health Insurance Assistance Program for information on all of your options. Content is for general information and is not a guarantee of coverage or rates; figures are subject to change by CMS and carriers.