When Medicare Open Enrollment Happens and What You Need to Do

Medicare Open Enrollment runs from October 15 to December 7 each year

Open Enrollment is the yearly window when you can change your Medicare coverage for the following year. During these dates, you can switch between Original Medicare and Medicare Advantage plans, add or drop prescription drug coverage, or move from one plan to another. If you do not make changes during Open Enrollment, your current plan continues into the next year without interruption.

The dates are the same every year: October 15 through December 7. Your changes take effect on January 1. This timing matters because plans change their costs, coverage, and networks every year — what worked for you in 2024 may cost more or cover less in 2025.

There are other enrollment windows for people in specific situations, but Open Enrollment is the main one for most seniors. Missing Open Enrollment usually means you cannot change plans until the following October, with limited exceptions.

Key Takeaways

Open Enrollment happens October 15 to December 7 each year, and changes take effect January 1.
You can switch between Original Medicare and Medicare Advantage, add or drop Part D drug coverage, or change to a different plan during this window.
If you miss Open Enrollment, you generally cannot change plans until October of the following year unless you have a may have access to life event.
Plans change their premiums, deductibles, and drug formularies every year, so reviewing your coverage annually protects you from unexpected costs.
You can compare plans and make changes online at Medicare.gov, by phone at 1-800-MEDICARE, or in person at your local Social Security office.

What you can change during Open Enrollment

During the October 15 to December 7 window, you have four main options. First, you can switch from Original Medicare (Part A and Part B) to a Medicare Advantage plan (Part C), or go the other direction from Medicare Advantage back to Original Medicare. Second, you can change from one Medicare Advantage plan to a different Medicare Advantage plan. Third, you can add Part D prescription drug coverage if you do not have it, or switch to a different Part D plan. Fourth, you can add or drop a Medigap supplemental insurance policy if you have Original Medicare.

You cannot change your Medigap plan during Open Enrollment in the same way you can change Medicare Advantage — Medigap has its own rules and enrollment periods. If you want to switch Medigap policies, you may face medical underwriting depending on your situation and state.

One important limit: if you are in a Medicare Advantage plan and want to switch to Original Medicare, you can do this during Open Enrollment. But if you then want to add a Medigap policy after switching to Original Medicare, you may not have the same protections against being denied or charged more based on your health history. Timing matters here, so understanding the sequence helps.

Special enrollment periods when you can change plans outside October

If you experience certain life events, you may be able to change your Medicare coverage outside of Open Enrollment. These windows are called Special Enrollment Periods, and they last 60 days from the date of the may have access to event. may have access to events include losing employer coverage, moving out of your plan's service area, getting married or divorced, losing a family member, or becoming may be able to access for Medicaid.

You must report the may have access to event to Medicare within 60 days to use a Special Enrollment Period. Contact Medicare at 1-800-MEDICARE or visit Medicare.gov to report the event and see what changes you can make. Some events, like moving to a new state, may open your window when ready. Others, like losing employer coverage, require documentation.

If you miss the 60-day window, you typically cannot change plans until the next Open Enrollment in October, even if the may have access to event was recent. This is why acting quickly matters if your situation changes.

How to compare plans and make changes

Medicare.gov has a tool called "Plan Finder" that lets you enter your current medications, doctors, and hospitals to see which plans cover them and what your costs would be. You can access Plan Finder starting in October each year. The tool shows you premiums, deductibles, copays, and whether your prescriptions are on each plan's formulary — the list of covered drugs.

You can also call 1-800-MEDICARE to speak with someone who will walk you through your options. Representatives can compare plans over the phone and answer questions about coverage. Many local Area Agencies on Aging also offer free counseling through the State Health Insurance information Program (SHIP), where trained counselors review your specific situation and help you decide.

Once you have chosen a plan, you can enroll online at Medicare.gov, by phone at 1-800-MEDICARE, or by mail using the enrollment form Medicare sends you. Online enrollment is usually fastest and shows you confirmation when ready.

What happens if you miss Open Enrollment

If you do not make changes during the October 15 to December 7 window, your current plan automatically continues into the new year. You will pay the same premiums and have the same coverage unless your plan changes its terms — which plans do every year. This means your out-of-pocket costs may increase, your deductible may change, or your doctor may no longer be in-network.

You cannot switch plans again until the next Open Enrollment in October, unless you have a may have access to life event that opens a Special Enrollment Period. If you realize in February that your new plan costs too much or does not cover your medications, you are generally locked in until October.

The exception is if you are in a Medicare Advantage plan and want to switch back to Original Medicare. You have until March 31 to make this switch if you did not do it during Open Enrollment — this is called the Medicare Advantage Open Enrollment Period, and it runs January 1 to March 31. This window exists because Medicare Advantage plans have different rules than Original Medicare, and the law gives you a second chance to switch back.

Important dates and important date to mark

October 15: Open Enrollment begins. You can start comparing plans and making changes.

December 7: Open Enrollment ends at 11:59 p.m. Eastern Time. This is your last day to make changes for the new year. If you enroll online, do it before midnight. If you call 1-800-MEDICARE, call before 8 p.m. Eastern Time to may support your call is processed that day.

January 1: Your new coverage takes effect. If you switched plans, your old plan ends and your new plan begins on this date.

January 1 to March 31: If you are in a Medicare Advantage plan and want to switch to Original Medicare, you can do so during this period without a may have access to event.

If you are already in Original Medicare and want to switch to Medicare Advantage, you must wait until the next Open Enrollment in October unless you have a may have access to life event.

Questions to ask your current plan before Open Enrollment

Before you compare other plans, contact your current plan and ask: Is my doctor still in-network next year? Are my medications on the formulary for next year? What are my premiums, deductible, and out-of-pocket costs for next year? Has my plan changed its coverage area? Some plans shrink their service areas or drop certain hospitals, which can affect you even if you do not switch.

Your plan should send you a notice in September or early October listing these changes. Read it carefully. If your doctor is leaving the network or your medication is no longer covered, that is a strong signal to compare other plans during Open Enrollment.

Frequently Asked Questions

What if I turn 65 during Open Enrollment?

If you turn 65 between October 15 and December 7, you have a separate Initial Enrollment Period that lasts seven months — three months before the month you turn 65, the month you turn 65, and three months after. You can enroll in Medicare during this window without waiting for Open Enrollment. Contact Social Security or Medicare.gov to start your enrollment.

Can I change my mind after I enroll in a new plan?

Yes, but only during Open Enrollment. If you enroll in a new plan on November 1 and change your mind on November 15, you can switch to a different plan before December 7. After December 7, you are locked into your choice until the next Open Enrollment in October, unless you have a may have access to life event.

Do I have to do anything if I want to keep my current plan?

No. Your current plan continues automatically on January 1 if you do not make changes. However, you should still review your plan's changes for the new year — premiums, deductibles, and formularies change annually, and you may find a better option during Open Enrollment.

What if my plan is being discontinued?

If your current plan is ending, Medicare will notify you by September. You must choose a new plan during Open Enrollment. Medicare will help you find similar coverage, and you will have until December 7 to enroll. If you do not choose a plan, Medicare will automatically move you to another plan in your area, but you may not like the choice.

Can I enroll in a plan after December 7?

Not unless you have a may have access to life event that opens a Special Enrollment Period. If you miss the December 7 important date, you will have to wait until October 15 of the following year. The only exception is if you are in Medicare Advantage and want to switch to Original Medicare — you can do that until March 31.

This guide is for general information only and is not medical, financial, legal, or other professional advice. For decisions specific to your situation, consult a qualified professional. See our Editorial Policy.