How to Switch Medicare Plans: Disenrollment, AEP & OEP Guide

Changing Medicare plans is hardly as easy as replacing your car insurance policy. There are also federal regulations about when you can switch coverage, what kind of plan you have determines which options are available to you, and the most important rule that many beneficiaries aren't aware of: Medigap supplement plans have different rules than Medicare Advantage and Part D plans. There are two main time periods in which Medicare beneficiaries can switch plans each year: the Annual Election Period, October 15 through December 7, when the changes become effective January 1, and the Medicare Advantage Open Enrollment Period (MA OEP), which is from January 1 through March 31, for individuals who are already enrolled in Medicare Advantage. In addition to these regular windows, the 5-Star Special Enrollment Period also lets you switch to a 5-star rated Medicare Advantage Plan or Part D Plan once a year, and a 12-month trial right ensures that anyone who enrolls in a Medicare Advantage Plan will be able to return to Original Medicare with guaranteed Medigap rights when the trial ends. For 2026, there is a new "inaccurate directory" SEP that lets you switch to a different MA plan if you find that your list of providers is wrong in your first 3 months with your MA plan.

This guide covers Medicare plan switching and enrollment periods, plus the Medigap underwriting trap for 2026. Data is provided by Medicare.gov, CMS and KFF research.

The Annual Election Period (AEP): October 15 - December 7

The Annual Election Period is the most important time each year to make changes to Medicare plans. AEP offers a wide range of plan changes options, from October 15 to December 7 annually. Any changes during AEP are effective Jan. 1 on the next successive year.

It's a good time to enroll in a Medicare Advantage plan during AEP, as you can convert from Original Medicare (Parts A and B). There are ways to change from a Medicare Advantage plan to Original Medicare. It is possible to change Medicare Advantage plans. It is possible to change from one Part D prescription drug plan to another. Part D coverage may be terminated entirely (although this will usually not be advisable unless creditable coverage has been obtained, or penalties for late enrollment apply).

The AEP doesn't apply to Medigap supplement plans. In most states, you can enroll in Medigap at any time in the year, but if you enroll outside of your 6-month Medigap Open Enrollment Period (after you turn 65 and enroll in Part B), you will be subject to medical underwriting.

AEP is a time when many beneficiaries don't actively shop around. Without your action, your coverage renews automatically for another year, but the plan might make changes to its formulary, provider network, premiums or cost-sharing that will impact you. Making comparisons each Fall keeps you safe from unexpected surprises.

See our enrollment periods guide for a complete overview of the enrollment periods. 

The Medicare Advantage Open Enrollment Period: January 1 - March 31

Medicare Advantage Open Enrollment Period (MA OEP) is only for individuals who are already enrolled with Medicare Advantage. MA OEP is the second chance to make changes after AEP has concluded from January 1 - March 31.

During MA OEP, current Medicare Advantage enrollees can switch to a different Medicare Advantage plan, return to Original Medicare (including a Part D plan) and enroll in a Part D plan if they return to Original Medicare.

Coverage for MA OEP begins the first day of the month after you make a request to join. Applications made in February will be effective from March 1. Submit in March – coverage begins April 1.

Note: MA OEP is not available for people who are currently in Original Medicare. MA OEP is the only time that Original Medicare can be changed to a Medicare Advantage plan. There is only one change allowed within MA OEP. When a change has been made, a subsequent change can only be made at the next enrollement.

If you need more detail on working past 65, please refer to our working past 65 guide. 

The Medigap underwriting trap

The biggest switching pitfall for Medicare beneficiaries is the Medigap underwriting trap. However, Medigap supplement plans have different federal rules, and AEP rules don't apply to them.

In many states, you can only purchase Medigap at a guaranteed time: your 6-month Medigap Open Enrollment Period, which starts when you are at least 65 and have first signed up for Part B. Once this 6-month period expires, medical underwriting is an option in most states that Medigap insurers can use to refuse coverage, increase premiums based on health status or impose waiting periods for pre-existing conditions.

You'll find that this sets up the "trap": If you first signed up for Medicare Advantage when you turned 65, you may have to experience medical underwriting if you choose to opt for Medicare Original Plan Part A or Medicare Part C (Original Medicare) at some time in the future. Over time, many Medicare Advantage enrollees develop chronic conditions which will lead to Medigap denial or rate-up.

There are some exceptions that afford Medigap rights within a longer time frame than the 6 months. There are guaranteed Medigap rights if you joined Medicare Advantage at the time you became eligible for Medicare and wish to enroll in Original Medicare within 12 months of your initial Medicare Advantage enrollment. This is a single-use right that is not applicable to people who have prior MA-then-Original transition.

Special circumstances, such as leaving your MA plan, relocating out of the plan's service area or a plan's decision to no longer provide coverage, give you guaranteed rights to enroll into a Medigap plan within 63 days of the situation. 

Several states have expanded Medigap rights beyond federal minimums. Connecticut, Massachusetts, and New York allow year-round guaranteed-issue Medigap enrollment regardless of health status. California, Idaho, Illinois, Maryland, Oregon, Nevada, Louisiana, Oklahoma, Utah, Virginia, Kentucky, Wyoming, Delaware (2026), and Indiana (2026) have "birthday rules" allowing time-limited annual windows for Medigap switching without underwriting. Washington allows Medigap switching at any time after 90 days of coverage.

The 5-Star SEP and other Special Enrollment Periods

The 5-Star Special Enrollment Period allows you to switch to a Medicare Advantage or Part D plan with a 5-star quality rating, once per year between December 8 and November 30. Fewer than 5% of plans earn 5 stars nationally.

CMS releases new star ratings each October for the following plan year. Check whether 5-star plans are available in your area using the Medicare.gov Plan Finder.

Other Special Enrollment Periods provide switching opportunities for specific life events. Moving to a different plan service area provides a 2-month SEP. Loss of Medicaid eligibility creates SEPs. Qualifying for or losing Extra Help triggers SEPs. Living in a skilled nursing facility creates monthly SEPs.

New for 2026: the "inaccurate directory" SEP allows you to switch from your Medicare Advantage plan if you discover its provider list was incorrect during your first 3 months of enrollment. This SEP requires documentation showing the directory inaccuracy.

For detailed SEP coverage, see our SEP guide.

How to switch from Medicare Advantage to Original Medicare

Switching from Medicare Advantage back to Original Medicare during AEP or MA OEP follows specific steps.

First, enroll in your new Part D plan or notify Social Security of your switch. Enrolling in a stand-alone Part D plan during AEP or MA OEP automatically disenrolls you from your current Medicare Advantage plan with Part D coverage.

Alternatively, you can call 1-800-MEDICARE or visit medicare.gov/account to disenroll from your MA plan directly. You'll need to enroll in a separate Part D plan if you want prescription drug coverage.

Once your disenrollment is processed, you return to Original Medicare (Parts A and B). Your Part B premium continues at $202.90 for 2026 standard premium.

Consider whether to add a Medigap plan. If you're within your 12-month trial period from initial MA enrollment, you have guaranteed Medigap rights. Otherwise, in most states, you'll face medical underwriting.

The transition should be timed carefully to avoid coverage gaps. Coverage typically starts the first of the following month for AEP changes (effective January 1) or following enrollment for MA OEP changes.

How to switch from Original Medicare to Medicare Advantage

Switching from Original Medicare to Medicare Advantage is straightforward during AEP. Choose your new Medicare Advantage plan using the Medicare.gov Plan Finder, comparing plans on premiums, networks, drug formularies, copays, and special benefits.

Enroll directly with the insurer or through a licensed Medicare Advantage agent. The enrollment process collects information including your Medicare claim number, doctor preferences, and prescription drug needs.

Once enrolled, you automatically disenroll from any prior Medicare Advantage plan or standalone Part D plan. You continue to pay your Part B premium ($202.90 standard 2026) directly to Medicare. You also pay your MA plan's premium (which may be $0 or higher) if applicable.

If you have a Medigap plan when switching to Medicare Advantage, you'll likely need to drop the Medigap plan because Medigap doesn't work with Medicare Advantage. Once dropped, you may lose your Medigap plan if you want to return.

For Medicare Advantage choices, see our Medicare Advantage guide.