Medicare Annual Enrollment Period runs from October 15 to December 7 each year

The Annual Enrollment Period (AEP) is the one time each year when you can change your Medicare coverage without a penalty. It always begins on October 15 and ends on December 7. Any changes you make during this window take effect on January 1 of the following year.

This is different from the Initial Enrollment Period, which is the seven-month window around your 65th birthday when you first become may be able to access for Medicare. AEP is for people already enrolled who want to switch plans, add coverage, or drop coverage they no longer need.

Outside of AEP, you can only change plans if you have a may have access to life event — such as losing employer coverage, moving to a new state, or becoming may be able to access for Medicaid. Without a may have access to event, changes made outside AEP will not take effect.

Key Takeaways

  • Medicare Annual Enrollment Period runs October 15 through December 7 each year, and changes take effect January 1.
  • You can switch from Original Medicare to a Medicare Advantage plan, move between Advantage plans, add or drop prescription drug coverage, or switch Medigap policies during AEP.
  • If you miss the October 15 important date, you cannot change plans until the following year unless you have a may have access to life event.
  • Medicare sends a notice in the mail before AEP begins, and you can review plan options on Medicare.gov or by calling 1-800-MEDICARE.

What you can change during Annual Enrollment Period

During AEP, you have four main options. You can switch from Original Medicare (Parts A and B) to a Medicare Advantage plan (Part C), which bundles hospital, medical, and usually prescription drug coverage through a private insurer. You can also go the opposite direction — drop your Advantage plan and return to Original Medicare.

If you are already in a Medicare Advantage plan, you can switch to a different Advantage plan offered by a different company. You can add Part D prescription drug coverage if you do not have it, or switch to a different Part D plan. If you have Original Medicare and a Medigap policy (supplemental insurance), you can switch to a different Medigap plan or drop it entirely.

One important limit: if you drop a Medigap policy during AEP and want to buy it back later, you may not have the same protections against being denied or charged more for pre-existing conditions. Check with your current insurer about what happens if you leave before you make the switch.

How to review plans before the important date

Medicare mails a notice to your home address in September or early October each year. This notice lists the plans available to you and any changes to your current plan's costs or coverage. Do not throw it away — it contains your plan's premium, deductible, and copay amounts for the coming year.

You can also compare plans yourself on Medicare.gov using the Plan Finder tool. Enter your zip code, current medications (if you are comparing Part D plans), and preferred doctors and hospitals. The tool shows you which plans cover those doctors and what your out-of-pocket costs would be under each option.

If you do not have internet access or prefer to talk to someone, call 1-800-MEDICARE (1-800-633-4227). Representatives can walk you through your options and answer questions about specific plans. The line is open seven days a week during AEP.

When to make your decision and how to enroll

You do not have to wait until December 7 to enroll. The earlier you make a change, the sooner you can confirm that your new plan has your doctors in its network and that your medications are covered. Many people enroll in mid-October or November to give themselves time to contact their new plan with questions before January 1.

You can enroll in three ways. Online, go to Medicare.gov, log into your account, and follow the steps to change your plan. By phone, call 1-800-MEDICARE and a representative will help you enroll over the call. In person, visit your local Social Security office or a State Health Insurance information Program (SHIP) office — SHIP counselors offer free help with plan selection and enrollment.

Once you enroll, your new plan will send you a welcome packet with your member ID card, plan documents, and a list of in-network doctors and pharmacies. Keep your old plan's card until January 1, when your new coverage begins.

What happens if you miss the October 15 important date

If December 7 passes and you have not made a change, you stay in your current plan for another year. You cannot switch plans again until the following October 15, unless you have a may have access to life event.

may have access to events include losing employer coverage, moving to a new state, becoming may be able to access for Medicaid or Extra Help (a program that helps pay for Part D), getting married or divorced, or having a significant change in your health status. If any of these happen, you have 60 days from the event to make a change. You will need to contact Medicare or your plan to report the event and request a Special Enrollment Period.

If you are newly may be able to access for Medicare (turning 65 or becoming may be able to access due to disability), your Initial Enrollment Period is seven months long — three months before the month you turn 65, the month itself, and three months after. That window is separate from AEP and does not follow the October 15 to December 7 schedule.

Common mistakes to avoid during enrollment

One frequent error is assuming your current doctor is in your new plan's network. Even if your doctor was in-network last year, they may have left the network or the plan may have changed its network. Before you enroll, call your doctor's office or use the plan's online directory to confirm they are listed as in-network for 2025.

Another mistake is not checking whether your medications are covered under the new plan's formulary (the list of covered drugs). A plan may have a lower premium but require you to pay more for your specific medications, or it may not cover them at all. Use the Plan Finder tool to check your medications before you enroll.

Do not wait until December 6 to enroll if you can help it. If you enroll on the last day and your new plan has questions about your process, there is no time to fix problems before January 1. Enrolling by early December gives you a buffer.

Frequently Asked Questions

Can I change plans more than once during Annual Enrollment Period?

Yes. You can change your mind and switch to a different plan as many times as you want between October 15 and December 7. Only your last change will take effect on January 1. However, once January 1 arrives, you are locked into that plan until the next AEP unless you have a may have access to life event.

What if I turn 65 during Annual Enrollment Period?

Your Initial Enrollment Period takes priority. You have seven months centered on your birthday month to enroll in Medicare for the first time. Once you are enrolled, you can also make changes during AEP if it falls within your seven-month window. Contact Medicare to make sure your enrollment is processed correctly.

Do I have to enroll in Part D during AEP if I do not take prescription drugs?

You are not required to, but there is a penalty if you go without Part D coverage and then enroll later. The penalty is 1% of the national average Part D premium for each month you were not enrolled. If you think you might need prescriptions in the future, enrolling now avoids this penalty.

Can my employer change my Medicare coverage during AEP?

If you are still working and covered under your employer's health plan, you may not be able to change your Medicare coverage without losing your employer coverage. Talk to your employer's benefits department before making any changes during AEP.

What if I enroll in a plan and then move to a different state?

Moving to a new state is a may have access to life event. You have 60 days from your move to change plans, even if it is outside AEP. Contact Medicare or your current plan to report your move and request a Special Enrollment Period so you can switch to a plan available in your new state.