If you’re purchasing a new Medicare health or prescription drug plan for 2025, or want to update your current plan, this guide will show you how, when and what changes you can make. You’ll get answers to all the essential Medicare Annual Enrollment Period (AEP) questions so you can make the best decision for you.

What is the Medicare Annual Enrollment Period?

The Medicare Annual Enrollment Period (AEP), also known as the Medicare Annual Election Period and the Medicare Open Enrollment Period, is a specific fall enrollment period from Oct. 15 through Dec. 7 (see calendar above). During this time, beneficiaries can make changes to their current Medicare plan coverage. All plan and benefit changes become effective on Jan. 1 the following year.

On Oct. 1 each year – two weeks before Medicare open enrollment starts – health insurance companies release information about their plan benefits for the following year. These can include premium changes, prescription drug coverage updates and more. This is a great time for Medicare beneficiaries to think about whether their plan will still meet their needs in the next year. If not, they can look for a better option during AEP.

You can make these changes without any review of your medical history, as you might need to do when switching Medicare Supplement plans.

What is the Medicare Open Enrollment Period?

Medicare Open Enrollment Period (OEP) can mean different things depending on how you use it. As mentioned above, it is often used to refer to AEP. But there is also a Medicare Advantage Open Enrollment Period (MA OEP). As the name implies, changes during this time – Jan. 1 through March 31 – are limited to Medicare Advantage plans and are only available to those that are currently enrolled in a Medicare Advantage plan.

What is the difference between AEP and OEP?

The biggest difference between AEP and OEP is that AEP offers more options and flexibility than the Medicare Advantage Open Enrollment Period. For example, during the MA OEP, you can join a Part D plan ONLY IF you are dropping an MA plan and returning to Original Medicare. However, during AEP, you can make any necessary changes to your drug coverage as needed.

What changes can you make during AEP?

During the Medicare Annual Enrollment Period, you can make changes to your Medicare Advantage and Cost plans, and Part D prescription drug plans only. Multiple changes and updates are allowed, including:

• Dropping your Medicare Advantage plan and returning to Original Medicare
• Moving from Original Medicare only to a Medicare Advantage plan
• Enrolling in a different Medicare Advantage plan
• Choosing a new Medicare Part D prescription drug plan
• Adding a Part D prescription drug plan if you don’t have one
• Canceling your current Part D prescription drug plan
  • Note: If you don’t maintain some form of creditable prescription drug coverage and decide to re-enroll in Part D in a later year, you’ll get dinged with a late-enrollment penalty.

There isn’t any special flexibility to add or adjust your Medicare Supplement (Medigap) plan during AEP. If you choose to change your Supplement plan during AEP, the same rules apply as they would during the rest of the year.

What changes can you make during OEP?

It depends on the context. If you are talking about the Medicare Annual Enrollment Period we talked about earlier, then you can make updates to your Medicare Advantage and Cost plans, and Part D prescription drug plans.

If you are talking about the Medicare Advantage Open Enrollment Period, then you can make these changes related to your current Medicare Advantage plan only:

• Switching to a different Medicare Advantage plan
• Dropping your Medicare Advantage plan and returning to Original Medicare
• Adding a standalone Part D plan – only if you dropped your Medicare Advantage plan and returned to Original Medicare

The MA OEP happens annually from Jan. 1 through March 31 and only applies to people who have coverage under a Medicare Advantage plan. Also, enrollees can only make one plan change during this annual window, in contrast to the fall annual enrollment period when enrollees can change their minds multiple times.

How do you change your Medicare plan during open enrollment?

If you’re switching plans during the AEP, simply join your new plan by contacting the insurance provider, a local health insurance broker, or enroll online if available. Then, you will automatically be disenrolled from your current plan on Dec. 31. Your new plan coverage will begin on Jan. 1.

If you’re switching plans during the MA OEP, simply join your new plan by contacting the insurance provider, a local health insurance broker, or enroll online if available. Then, contact your current plan provider to find out how to disenroll from your current plan. Your new plan coverage will begin on the first of the following month. For example, if you enroll on Feb. 18, your new plan will be effective on March 1.

To switch to Original Medicare, contact your current plan administrator, or visit medicare.gov.

What happens if you miss Medicare Open Enrollment?

If you miss the opportunity to change your plan during the AEP or MA OEP, you’ll need to keep your current plan for one more year, until the next open enrollment period.

However, you may still be able to make changes to your Medicare coverage if you qualify for a special enrollment period. An example of this could be if you lose health insurance coverage from your employer or your spouse’s employer.

If you don’t qualify for a Medicare special enrollment period, you’ll need to wait for the next relevant Medicare open enrollment period to make changes to your Medicare health or prescription drug plan.

Do you have to re-enroll in Medicare every year?

No. You don’t have to re-enroll in Medicare every year and you don’t have to renew your Medicare Advantage, Supplement or prescription drug plan either. You only need to act if you’re notified to do so – for example, if your plan is discontinued or if there is a reduction in your service area.

Can you enroll in Medicare for the first time during Medicare Open Enrollment?

If you’re buying a Medicare plan for the first time, you can do so during your Medicare Initial Enrollment Period (IEP). If your IEP happens to overlap with the Oct. 15 – Dec. 7 Medicare Open Enrollment Period, you may enroll for the first time.

You may also be able to enroll in a Medicare plan at different times during the year if you qualify for a special enrollment period.