Every fall, millions of people with Medicare let the Annual Enrollment Period come and go without touching their plan. Most of them assume that doing nothing means nothing changes.
That's the most expensive misunderstanding in Medicare.
Doing nothing during AEP is actually a decision: a decision to accept every change your plan has scheduled for 2027, sight unseen. Your plan will renew automatically on January 1, but the plan you wake up with may have different premiums, different copays, a smaller provider network, new prior authorization requirements, and a reshuffled drug formulary.
Here's exactly what happens when you skip the 2027 AEP, the changes that can hit you in January, and the backup options you still have if you miss the window.
First, the 2027 AEP Dates
The Annual Enrollment Period for 2027 coverage runs October 15 through December 7, 2026. Any change you make takes effect January 1, 2027.
Before that window opens, your plan is required to mail you an Annual Notice of Change (ANOC). It should arrive by September 30, 2026. That document is the plan's official confession of everything it's changing next year.
For the full timeline and a prep checklist, see our guide to the 2027 Medicare Annual Enrollment Period key dates.
What Actually Happens If You Skip AEP
If you take no action by December 7, 2026, one of two things happens:
- Your plan still exists in 2027. You're automatically re-enrolled in the same plan, under its new 2027 terms. Everything in the ANOC applies to you on January 1, whether you read it or not.
- Your plan is being discontinued. If your Medicare Advantage plan is leaving your county or shutting down, you'll get a non-renewal notice. Do nothing here and you'll typically be moved to Original Medicare on January 1, often without drug coverage, unless you act. (This situation grants you a Special Enrollment Period, covered below.)
Auto-renewal sounds convenient. The problem is what rides along with it.
Five Changes That Can Hit You on January 1
These are the changes that most often surprise people who auto-renewed. Every one of them is disclosed in the ANOC.
1. Higher premiums and copays
Plans routinely raise monthly premiums, specialist copays, hospital per-day charges, and the annual out-of-pocket maximum. A "$0 premium" plan can stay $0 while quietly raising the out-of-pocket maximum by hundreds or thousands of dollars.
2. Your doctor leaves the network
Provider networks are re-negotiated every year. The primary care doctor or specialist you've seen for a decade may be out-of-network in 2027, which for most Medicare Advantage plans means paying far more, or paying everything, to keep seeing them.
3. Your drugs move to a more expensive tier
Formularies get reshuffled annually. A generic that cost you $5 can move to a higher tier, gain a quantity limit, or be dropped from coverage entirely.
4. New prior authorization requirements
Services that didn't need advance approval in 2026 can require it in 2027: imaging, procedures, skilled nursing care, home health. More prior authorization means more chances for a denial. If you're not familiar with how that process works, read our plain-English guide to Medicare prior authorization.
5. Reduced extra benefits
Dental, vision, hearing, transportation, and over-the-counter allowances are the benefits plans advertise hardest, and trim quietest. The ANOC is where those cuts are disclosed.
If two or more of these apply to you, it's worth a serious look at your options. Our companion guide walks through whether you should switch Medicare Advantage plans for 2027 using your ANOC as the starting point.
"I Missed AEP": Your Backup Options
Missing the December 7 deadline doesn't always mean you're locked in for the whole year.
- Medicare Advantage Open Enrollment (January 1 to March 31, 2027). If you're in a Medicare Advantage plan, you get one switch during this window: to a different Medicare Advantage plan, or back to Original Medicare (plus a standalone drug plan). One change only, and it takes effect the first of the month after the plan gets your request.
- Special Enrollment Periods (SEPs). Certain events open a personal enrollment window: your plan leaves your area, you move out of the plan's service area, you qualify for both Medicare and Medicaid, or you qualify for Extra Help with drug costs, among others.
- 5-star plans. If a 5-star-rated plan is available where you live, you can switch into it once per year outside AEP.
These are real escape hatches, but they're narrower than AEP. The five-star option requires a five-star plan in your area, SEPs require a qualifying event, and the January to March window gives you exactly one move. AEP is still the only time everyone can make any change.
Doing Nothing Doesn't Protect You From Denials
Here's the part most AEP articles skip: staying put doesn't mean your coverage behaves the way it did last year.
Because prior authorization rules and coverage criteria reset with the new plan year, people who changed nothing still see new denials in January and February, for the same services, from the same plan, sometimes ordered by the same doctor.
If that happens to you, don't accept it as final. Most denials that get appealed are worth appealing, and Medicare Advantage appeals have strict deadlines: you have 65 calendar days from the date on the denial notice to file a Level 1 appeal. Our free Medicare denial appeal letter template shows you exactly what to send.
The 20-Minute "Do Nothing" Safety Check
If you've read this far and still plan to keep your plan, fine, but make it an informed decision. Before December 7:
- Find your ANOC (mailed by September 30; also available in your plan's online portal).
- Check the money page: premium, out-of-pocket maximum, and copays for the services you actually use.
- Search the 2027 provider directory for your doctors and hospital.
- Check the 2027 formulary for each of your prescriptions: tier, restrictions, and pharmacy rules.
- Scan for new prior authorization requirements on services you expect to need.
If everything checks out, doing nothing is a legitimate choice. If it doesn't, you have until December 7, 2026 to fix it.
FAQ
What happens if I don't do anything during Medicare AEP?
Your current plan automatically renews for 2027 under its new terms: new premiums, copays, network, formulary, and prior authorization rules all take effect January 1, 2027. If your plan is being discontinued, you'll typically be moved to Original Medicare unless you choose a new plan.
What are the AEP 2027 dates?
The Annual Enrollment Period for 2027 coverage runs October 15 through December 7, 2026. Changes take effect January 1, 2027.
Can I change my Medicare Advantage plan after December 7?
Possibly. The Medicare Advantage Open Enrollment Period (January 1 to March 31, 2027) allows one switch, and Special Enrollment Periods cover events like moving or losing your plan. Otherwise, you generally wait until the next AEP.
Do I have to re-enroll in Medicare every year?
No. Enrollment is automatic year to year. But your plan's costs and rules change every January, which is why reviewing your Annual Notice of Change each fall matters even if you never switch.
My plan denied a service in January that it covered last year. Can I fight it?
Yes. Coverage rules reset with each plan year, and new-year denials are common, and they are appealable. You have 65 calendar days from the date on a Medicare Advantage denial notice to file a Level 1 appeal.
Denied? You don't have to fight alone.
DENIED. — The Insider's Manual to Winning Your Medicare Advantage Appeal walks you through every step and includes 5 ready-to-send appeal letters you can fill in and mail today.
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This article is general education, not legal or medical advice. Medicare rules, deadlines, and dollar amounts change; confirm the current details for your situation at Medicare.gov or by calling 1-800-MEDICARE. MedicareClaimDenied.com is not affiliated with or endorsed by Medicare, CMS, or any insurer.