Introduction
Medicare isn't a "set it and forget it" benefit. Premiums shift, provider networks narrow or expand, formularies change, and cost-sharing rules get rewritten every single year.
That's exactly why the fall Annual Enrollment Period matters. It's your yearly checkpoint to ask: will my current coverage still work for me next year?
This guide walks through the official AEP dates, what you're actually allowed to change, how AEP differs from the Medicare Advantage Open Enrollment Period, and what your options look like if you miss the deadline entirely.
Key Takeaways
- AEP runs October 15 through December 7, with changes effective January 1 (confirm dates at Medicare.gov).
- You don't have to switch plans, but still read your Annual Notice of Change.
- AEP mainly affects Medicare Advantage and Part D; Medigap changes use separate underwriting rules.
- Compare total costs, drug coverage, and provider networks, not just the premium.
What Is the Medicare Annual Enrollment Period and When Does It Happen?
The Annual Enrollment Period, also called the Annual Election Period, is the yearly window when Medicare beneficiaries can review and change their Medicare Advantage and Part D prescription drug coverage. It's the one stretch of the calendar built specifically for comparison shopping.
The Standard Timeline
According to Medicare.gov's official open enrollment page, AEP runs from October 15 through December 7 each year. Coverage changes made during this window generally take effect January 1 of the following year, provided the plan receives your request by the December 7 deadline.
For AEP occurring in fall 2026, that means:
- Start date: October 15, 2026
- End date: December 7, 2026
- New coverage effective date: January 1, 2027
Always verify these dates directly through Medicare.gov before making a decision, since rules can be updated.
Why the ANOC and EOC Matter
Every fall, your current plan sends two documents you shouldn't toss in the junk mail pile:
- Annual Notice of Change (ANOC): Outlines what's changing next year, including premiums, deductibles, copayments, provider networks, covered drugs, and benefits.
- Evidence of Coverage (EOC): Spells out exactly what your plan covers and what you'll pay for it.
Plans typically send these by September 30, so you'll have several weeks to review them before AEP even opens.
One important distinction: AEP is not the same as the Initial Enrollment Period for first-timers, nor does it cover every Special Enrollment Period trigger. If you're newly eligible for Medicare or just experienced a qualifying life event, you may need a different enrollment window entirely.
What Can You Change During Medicare AEP?
What you're allowed to do during AEP depends heavily on where you're starting from. Before comparing anything, identify whether you currently have Original Medicare, Medicare Advantage, a standalone Part D plan, or a Medicare Supplement policy.
If You Have Original Medicare
You can:
- Join a Medicare Advantage plan, with or without drug coverage
- Add a standalone Part D prescription drug plan
Eligibility and late-enrollment rules still apply, so check them before switching.
If You Already Have Medicare Advantage
You can:
- Switch to a different Medicare Advantage plan
- Drop Medicare Advantage and return to Original Medicare (you'll likely need a standalone Part D plan at the same time; Medigap may require medical underwriting)
If You Have a Medicare Supplement (Medigap)
You can:
- Keep your Medigap policy and add or switch a standalone Part D plan
- Leave Medigap and enroll in a Medicare Advantage plan instead
AEP itself does not create a guaranteed-issue window to switch Medigap plans. In most states, buying a new Medigap policy can mean medical underwriting.
Part D-Specific Options
Regardless of your starting point, AEP lets you:
- Join a standalone prescription drug plan
- Switch from one Part D plan to another
- Move drug coverage between a standalone plan and one bundled into Medicare Advantage
- Drop drug coverage altogether
Be careful with that last one. Going 63 or more consecutive days without creditable drug coverage can trigger a Part D late-enrollment penalty.
Per Medicare's official penalty fact sheet, the penalty equals 1% of the national base beneficiary premium for each full uncovered month. That amount is added to your premium for as long as you have Part D coverage. The 2026 base premium used in this formula is $38.99.
What AEP Does Not Do
- No guaranteed right to switch Medigap policies without medical underwriting
- Does not replace the Initial Enrollment Period for someone newly eligible for Medicare
And if your current plan still fits your needs and remains available next year? You're allowed to do nothing. No change is required.
What Is the Difference Between AEP and MA OEP?
AEP isn't the only enrollment window on the Medicare calendar. The Medicare Advantage Open Enrollment Period (MA OEP) runs January 1 through March 31 and serves a much narrower purpose.
| Feature | AEP | MA OEP |
|---|---|---|
| Dates | October 15 – December 7 | January 1 – March 31 |
| Who can use it | Any Medicare enrollee | Only people already enrolled in Medicare Advantage |
| Permitted changes | Switch MA plans, move between Original Medicare and MA, join/switch/drop Part D | One change only: switch MA plans, or drop MA and return to Original Medicare |
| Cannot do | — | Cannot move from Original Medicare into Medicare Advantage |
| Effective date | January 1 of the next year | First day of the month after the plan receives the request |
The practical takeaway: AEP is your broad review window. MA OEP is a narrow safety net. If you made a rushed decision in December and want to reconsider by March, MA OEP gives you one shot at a correction—but only if you're already in Medicare Advantage.
Don't treat MA OEP as a substitute for doing your homework in the fall. A rushed AEP decision followed by an MA OEP fix still means months of coverage that may not match your needs.
How to Prepare for AEP and Compare Medicare Plans
Solid plan comparisons start before AEP opens, not during the last week of it.
Gather Your Documents First
Before comparing anything, collect:
- Your current plan's Annual Notice of Change (ANOC) and Evidence of Coverage (EOC)
- Your Medicare card
- A complete medication list (names, dosages, frequency)
- Preferred pharmacies
- Names of doctors, specialists, and hospitals you use
- Any anticipated procedures or changes in health status
Compare Total Costs, Not Just Premiums
A low monthly premium can hide higher costs elsewhere. Use official plan documents, not rough estimates, to compare:
- Premiums, deductibles, and copayments
- Coinsurance percentages
- Drug costs under the plan's formulary
- The plan's maximum out-of-pocket limit, where applicable
Verify Provider Networks Carefully
Medicare Advantage plans often require in-network care for non-emergency services. Check:
- Whether your doctors and preferred hospitals participate
- Referral requirements (generally required for HMOs, typically not for PPOs)
- Service area boundaries, especially important if you split time between states
- Out-of-network cost rules
Check Prescription Coverage Line by Line
For each medication, verify:
- Formulary status and cost tier
- Quantity limits
- Prior authorization requirements
- Step therapy rules
- Which pharmacies are in-network
- Estimated yearly cost under that specific plan
Don't Let Extras Distract You
Dental, vision, hearing, transportation, and fitness benefits are nice additions, but they shouldn't overshadow the fundamentals: medical coverage, provider access, drug coverage, and cost-sharing.
This is where many people get overwhelmed. Wareheim Medicare Advisors, based in Seminole, Florida, offers personalized, no-cost brokerage assistance and annual plan reviews so you can weigh healthcare needs, budget, and provider preferences together.
Availability and licensing vary by state, so confirm coverage details for your location before scheduling.
Common AEP Mistakes and What Happens If You Miss the Deadline
Most AEP mistakes aren't dramatic. They're small oversights that compound into a year of paying more than necessary.
The Mistakes Worth Avoiding
- Assuming your plan won't change. It almost always does, even slightly.
- Skipping the ANOC. This document tells you exactly what's different for next year.
- Choosing based on premium alone. A cheap plan with a narrow network or poor drug coverage isn't actually cheap.
- Not double-checking prescriptions and providers. This is where most surprise costs originate.
- Waiting until the last few days. Applications submitted late in the window face processing delays and leave less time to fix errors.
According to KFF's analysis of CMS Medicare Current Beneficiary Survey data, 69% of Medicare beneficiaries did not compare their existing coverage against other available options during a recent AEP.
Among Medicare Advantage prescription drug plan enrollees specifically, 82% skipped comparing their drug coverage against alternatives.
Comparing plans is only half the job. Submitting an application isn't the finish line either. Keep your confirmation materials, and double-check your new plan's effective date and enrollment details once they arrive.
If You Miss the Deadline
Generally, you'll stay in your current plan for the next coverage year—unless another enrollment opportunity applies. Options that might still be available include:
- MA OEP (January 1 – March 31), if you're already in Medicare Advantage
- A Special Enrollment Period, triggered by events like losing employer coverage, relocating, or a change in Medicaid eligibility
If you've missed AEP and one of these situations applies to you, don't assume you're stuck. Contact Medicare.gov directly, or reach out to a licensed advisor like Jim Wareheim at Wareheim Medicare Advisors, (727) 591-3900, to check what's still on the table.
Frequently Asked Questions
What is the AEP in Medicare?
AEP, or the Annual Enrollment Period, runs October 15 through December 7 each year. It's when eligible beneficiaries can review or change their Medicare Advantage and Part D prescription drug coverage.
What is the difference between AEP and MA OEP?
AEP is a broad fall window open to all Medicare enrollees. MA OEP runs January 1 through March 31 and only allows people already in Medicare Advantage to make one additional change.
What are the dates for Medicare AEP in 2026?
The AEP occurring in fall 2026 runs October 15 through December 7, 2026, with new coverage effective January 1, 2027. Confirm this through Medicare.gov before enrolling.
Do I have to change my Medicare plan during AEP?
No. If your current plan still meets your needs, you can keep it. Even so, review your Annual Notice of Change (ANOC), costs, provider network, and prescription coverage before you decide to stay put.
What happens if I miss the Medicare Annual Enrollment Period?
You'll generally remain in your current plan until the next applicable enrollment period. A Special Enrollment Period or MA OEP may open up additional options depending on your specific circumstances.
