Medicare Advantage Annual Enrollment Period (AEP): Key Dates and What You Need to Know

Understanding the Medicare Advantage Annual Enrollment Period (AEP)

Every fall, Medicare beneficiaries across the country gain access to a window that could meaningfully change their healthcare costs and coverage for the following year. That window is the Medicare Advantage Annual Enrollment Period (AEP) and knowing how to use it well makes a real difference.

The AEP runs from October 15 through December 7 each year. During this period, anyone with Medicare can join, switch, or drop a Medicare Advantage (Part C) plan or a Medicare Part D prescription drug plan. Any changes made take effect on January 1 of the following year.

For 2027 coverage, that means the AEP window is October 15 – December 7, 2026. This is the primary opportunity for existing Medicare beneficiaries to step back, review their current plan, and make sure it still fits their health needs and budget. Plans change every year, and so do your needs.

Key Dates and Deadlines for the 2027 AEP

The official AEP dates for 2027 coverage are October 15 through December 7, 2026. Any plan changes you submit during this period will become effective on January 1, 2027.

Missing the December 7 deadline has real consequences. Once AEP closes, your options for changing coverage become very limited, typically restricted to the Medicare Advantage Open Enrollment Period or a qualifying Special Enrollment Period. Acting within this window is not just advisable; for most beneficiaries, it’s the only practical time to make meaningful changes to their coverage.

Who is Eligible to Participate in AEP?

Any Medicare beneficiary already enrolled in Medicare Parts A and B is eligible for AEP. You don’t need to take any action to become eligible; it applies to you automatically each fall.

AEP is specifically for people who are already enrolled in Medicare. If you’re turning 65 or enrolling in Medicare for the first time, you’ll use the Initial Enrollment Period instead. That’s a separate, seven-month window centered around your 65th birthday, not AEP.

What Changes Can You Make During AEP?

AEP gives you broad flexibility to adjust your Medicare coverage. You are not locked into whatever plan you have now. Here’s a clear breakdown of what you can do.

During AEP, you can make the following changes:

• Switch from Original Medicare to a Medicare Advantage plan

• Switch from one Medicare Advantage plan to a different Medicare Advantage plan

• Switch from a Medicare Advantage plan back to Original Medicare

• Join a Medicare Part D prescription drug plan for the first time

• Switch from one Part D plan to another

• Drop your Part D coverage entirely

All of these changes take effect January 1, 2027. You can make multiple changes during AEP, but only your last submitted change before December 7 will be the one that takes effect.

Medicare Advantage Plan Changes

If you’re currently enrolled in a Medicare Advantage plan, AEP lets you evaluate whether that plan is still working for you. You can enroll in a completely different Medicare Advantage plan, switch between plan types (such as from an HMO to a PPO), or disenroll entirely and return to Original Medicare.

For those on Original Medicare who have been considering Medicare Advantage, this is also your primary window to enroll. Comparing Original Medicare and Medicare Advantage carefully before switching helps you avoid unexpected coverage gaps or network restrictions. Changes take effect January 1, 2027.

Medicare Part D Prescription Drug Coverage Adjustments

Drug coverage can shift significantly from year to year. Insurers update their formularies, the list of covered medications, annually. A drug that was covered in 2026 may be placed on a higher cost tier or removed from coverage entirely in 2027; however, plans are required to notify you of these changes.

During AEP, you can join a Part D plan, switch to a plan with a better formulary match, or drop coverage if your situation warrants it. Before making any decision, pull the 2027 formulary for any plan you’re considering and confirm your specific medications are covered at a cost you can manage.

Your Essential AEP Preparation Checklist for 2027

Walking into AEP without preparation is the most common way to end up in a plan that doesn’t fit your needs. Use the steps below to build a clear picture of your options before December 7, 2026.

Review Your Annual Notice of Changes (ANOC)

Each September, your current plan is required to send you an Annual Notice of Changes (ANOC) document. This is one of the most useful documents you’ll receive all year. It outlines exactly what is changing in your plan for 2027, including premiums, deductibles, copayments, covered services, and any network changes.

Read it carefully. Look specifically for:

• Premium increases or decreases

• Changes to your deductible or out-of-pocket maximum

• New or removed covered services

• Copayment or coinsurance changes for services you use regularly

• Updates to your prescription drug formulary

If your plan’s costs are going up significantly or key benefits are being reduced, AEP is your opportunity to find something better. You can learn more about what changes to expect each year during Medicare enrollment and how to read the ANOC effectively.

Assess Your Healthcare Needs for 2027

Your health situation this year may be different from last year. Take time to think through what you’ll actually need from your coverage in 2027. Are you seeing any new specialists? Have you been diagnosed with a condition that requires ongoing treatment? Do you anticipate any procedures or surgeries?

Make a list of your current doctors and confirm whether they participate in the network of any plan you’re considering. A plan with a lower premium can quickly become more expensive if your preferred doctors are out-of-network.

Compare Plan Options Using Reliable Tools

The official Medicare Plan Finder at Medicare.gov is the most reliable starting point for comparing plans available in your ZIP code. You can enter your medications and preferred pharmacies to get a side-by-side cost comparison that accounts for premiums, deductibles, and estimated drug costs.

When comparing plans, look beyond the monthly premium. Evaluate:

• Annual out-of-pocket maximum

• Copays for primary care and specialist visits

• Drug formulary coverage for your specific medications

• Network of hospitals and specialists

• Extra benefits like dental, vision, and fitness programs

You can also use our key questions to ask when comparing Medicare Advantage plans guide to make sure you’re covering all the right comparison points before committing to a plan.

Make Your Decision by December 7, 2026

The December 7 deadline is firm. Once AEP ends, you generally cannot make changes until the next enrollment window, unless you qualify for a Special Enrollment Period.

If you take no action, your current plan will typically auto-renew for 2027. That sounds convenient, but it carries real risk. Your plan may have changed its benefits, costs, or network, and auto-renewal means accepting those changes without review. Give yourself at least a few days before the deadline to make a final decision with a clear head.

Understanding Other Medicare Enrollment Periods

AEP is the most widely used enrollment window, but it isn’t the only one. Knowing when other periods apply helps you plan ahead and avoid missed opportunities.

The Medicare Advantage Open Enrollment Period (OEP) runs from January 1 through March 31 each year. During OEP, you can switch from one Medicare Advantage plan to another, or drop Medicare Advantage and return to Original Medicare. However, if you are switching from one Medicare Advantage plan to another, or returning to Original Medicare, you cannot use OEP to add or switch standalone Part D plans, nor can you use it to join Medicare Advantage for the first time.

Special Enrollment Periods (SEPs) are triggered by specific life events, such as moving to a new service area, losing other creditable coverage, or qualifying for Extra Help. SEPs allow coverage changes outside of AEP when circumstances warrant. You can explore all Medicare enrollment periods to see which windows apply to your situation.

Common Mistakes to Avoid

For a deeper dive into enrollment pitfalls, read our guide on the top 5 mistakes people make during Medicare annual enrollment and how to avoid them.

Consequences of Inaction During AEP

Doing nothing during AEP is itself a choice, and it has consequences worth understanding. If you don’t submit any changes by December 7, 2026, your current Medicare Advantage or Part D plan will automatically renew for 2027.

That automatic renewal may sound harmless, but plan terms can shift meaningfully between years. Your premium could increase, a medication could move to a higher cost tier, or a specialist you see regularly could leave the network. You would enter 2027 locked into a plan that no longer matches your situation.

Once AEP closes, your options narrow significantly. You can only make changes during the Open Enrollment Period (January 1 – March 31) or if a qualifying life event triggers a Special Enrollment Period. Neither option is as flexible as AEP. Taking even a few hours during the October 15 – December 7 window to review your coverage can prevent months of frustration, and potentially significant cost, in 2027.

Frequently Asked Questions About AEP

Conclusion: Make 2027 Coverage Work for You

The Medicare Advantage Annual Enrollment Period is one of the most consequential windows in your healthcare year. Plans evolve, costs shift, and your health needs change — AEP is the time to make sure your coverage keeps pace with all of it.

For 2027 coverage, the window is October 15 through December 7, 2026. Use that time to read your ANOC, assess your health needs, compare your options, and make a decision that fits your actual situation — not just the plan you happened to be in last year.

Taking a few focused hours during AEP can translate into better coverage, lower costs, and fewer surprises in 2027. If you want personalized guidance, speaking with a licensed Medicare agent or using your state’s SHIP program can help you compare plans with confidence. The deadline is firm, but the process, when approached step by step, is manageable.