Medicare Advantage Open Enrollment (OEP) – January 1 to March 31

Medicare advantage open enrollment gives current Medicare Advantage members a chance to rethink their coverage each year. This period runs from January 1 through March 31, 2026. It exists specifically for people already enrolled in a Medicare Advantage plan. During these three months, you can make one coverage change. You might switch to a different Medicare Advantage plan.

You might return to Original Medicare instead. You can also add or drop Part D prescription drug coverage as part of your change. This window matters because it may be your only opportunity to fix a coverage decision that is not working. If your current plan changed its network, formulary, or costs for 2026, this is your time to act. Missing this deadline could lock you into a plan that no longer fits your needs for the rest of the year.

When Is the Medicare Advantage Open Enrollment?

The medicare advantage open enrollment period begins on January 1 and ends on March 31 every year. For 2026, that gives you exactly 90 days to evaluate your options and make a change. Any enrollment request submitted during this window takes effect the first day of the following month. That means a change made in January starts February 1. A change made in March starts April 1.

Do not confuse the MA OEP with the Annual Enrollment Period. The AEP runs from October 15 to December 7 and is open to all Medicare beneficiaries. The medicare advantage open enrollment period in January through March is only for people who already have a Medicare Advantage plan.

Who Is Eligible During This Period?

You must already be enrolled in a Medicare Advantage plan to use this period. That includes Medicare Advantage plans with or without drug coverage. It also includes HMO, PPO, and PFFS plan types. You must have both Medicare Part A and Part B. You must live in the service area of any new plan you want to join.

Some people are not eligible to use the medicare advantage open enrollment window. Those enrolled in Medicare Medical Savings Account plans cannot participate. People in Medicare Cost Plans or PACE programs are also excluded. If you are in Original Medicare and want to join a Medicare Advantage plan, you need to use the AEP or a Special Enrollment Period instead.

New Medicare beneficiaries who joined a Medicare Advantage plan during their Initial Enrollment Period are eligible. However, they may also have a separate trial right that allows them to switch back to Original Medicare within 12 months of joining their first MA plan.

What Can You Do During the Medicare Advantage Open Enrollment?

During the medicare advantage open enrollment period, you are allowed exactly one plan change. This is a strict one-change limit. Once you submit an enrollment request and it is accepted, your choice is final for the rest of 2026. Choose carefully before you act.

Your options during this period include three main actions. First, you can switch from your current Medicare Advantage plan to a different Medicare Advantage plan. Second, you can drop your Medicare Advantage plan entirely and return to Original Medicare. If you return to Original Medicare, you can also enroll in a standalone Part D prescription drug plan at the same time. Third, you can switch to a Medicare Advantage plan that includes drug coverage if your current plan does not.

You cannot use this period to enroll in Medicare Advantage for the first time. You also cannot switch from Original Medicare into a Medicare Advantage plan. This window is exclusively for people who are already in an MA plan and want to make an adjustment.

What Happens If You Miss This Deadline?

If you miss the March 31 deadline for the medicare advantage open enrollment period, you will generally stay in your current plan until the next AEP. The Annual Enrollment Period does not open again until October 15, 2026. That means you could be locked into your current coverage for seven more months.

There are limited exceptions. You may qualify for a Special Enrollment Period if you experience a qualifying life event. Examples include moving out of your plan’s service area, losing employer coverage, or qualifying for Medicaid. Without a qualifying event, you must wait.

If you drop Medicare Advantage and return to Original Medicare without adding Part D, you could face a late enrollment penalty later. The Part D penalty in 2026 is 1% of the national base beneficiary premium per uncovered month. The national base beneficiary premium is $38.99 in 2026. That adds roughly $0.39 per month for every month you went without creditable drug coverage. This penalty is permanent and stays on your premium for life.

Step-by-Step: How to Enroll

Step 1: Review your current plan’s 2026 benefits. Check your Annual Notice of Change document for any differences in premiums, copays, networks, or drug formularies. Step 2: Compare available plans in your area. Use the Medicare Plan Finder at medicare.gov to search by ZIP code. Step 3: Make a list of your doctors and prescriptions. Confirm they are covered by any new plan you are considering.

Step 4: Choose your new plan and enroll. You can enroll online at medicare.gov, call 1-800-MEDICARE (1-800-633-4227), or contact the plan directly. TTY users can call 1-877-486-2048. Step 5: Confirm your enrollment. You should receive a confirmation letter from your new plan. Keep this document for your records. Your new coverage will start the first of the month after your plan receives your request.

Have these documents ready before you start: your Medicare card (red, white, and blue card), your current plan member ID card, a list of your current medications with dosages, and the names and addresses of your doctors. Having this information prepared saves time and reduces errors during enrollment.

Common Mistakes to Avoid

The biggest mistake during medicare advantage open enrollment is waiting too long to act. The March 31 deadline is firm. There are no extensions or grace periods. If you submit your enrollment request on April 1, it will not be processed under the MA OEP. Start your research in January so you have time to make an informed decision.

Another common error is not checking provider networks. A plan with a lower premium may not include your current doctors. Always verify that your preferred physicians and hospitals are in-network before switching. Failing to check the drug formulary is equally risky. Your current medications may not be covered under a new plan, or they may be placed on a higher cost tier.

Some people forget that the medicare advantage open enrollment allows only one change. If you switch plans in January and then realize you made the wrong choice, you cannot switch again in February. Your first accepted enrollment request is your only one for this period. Also, do not assume your Medigap options will be available. If you drop Medicare Advantage and return to Original Medicare, you may not have guaranteed-issue rights for a Medigap policy in most states.

Frequently Asked Questions

Can I use the medicare advantage open enrollment to join a Medicare Advantage plan for the first time?

No. This period is only for people already enrolled in a Medicare Advantage plan. If you are in Original Medicare and want to join an MA plan, you must use the Annual Enrollment Period from October 15 to December 7, or qualify for a Special Enrollment Period.

How many changes can I make during the medicare advantage open enrollment period?

You are limited to one change. Once your new enrollment request is accepted, that decision is locked in for the rest of 2026. You cannot make a second switch during this same period, so review your options thoroughly before submitting.

When does my new coverage start if I make a change during the medicare advantage open enrollment?

Your new coverage begins on the first day of the month after your plan receives your enrollment request. For example, if you enroll on February 10, 2026, your new plan coverage starts March 1, 2026. Your old plan continues until the new one begins.

What happens to my prescription drug coverage if I switch back to Original Medicare during this period?

If your Medicare Advantage plan included drug coverage and you switch back to Original Medicare, you will lose that drug benefit. You can enroll in a standalone Medicare Part D plan at the same time. If you do not enroll in Part D and go without creditable drug coverage, you may face a permanent late enrollment penalty of 1% per uncovered month added to your future premiums.

Compare Medicare Plans

Ready to explore your Medicare options? Use the official Medicare Plan Finder or contact your local SHIP counselor for free, unbiased help.

Official Sources & Resources

For verified Medicare information and enrollment help:

• Medicare.gov: medicare.gov
• CMS.gov: cms.gov
• NAIC Medigap Guide: naic.org
• KFF Medicare Research: kff.org/medicare
• Find Your SHIP: medicare.gov/contacts

Content last reviewed April 2026. If you notice any outdated information, please contact us.

Related Guides

• Browse All Medicare Guides
• More in This Category
• Medicare by State
• Medigap Plans by State
• Medicare Advantage by State
• Helping Parents With Medicare
• Medicare Costs & Premiums
• Idaho Medicare Guide
• Georgia Medicare Guide
• Tennessee Medigap Plans Guide