Medicare Advantage Disenrollment Period: When and How to Leave Your Plan

If your parent wants to leave their Medicare Advantage plan — whether they're unhappy with coverage, their plan is leaving their area, or they want to switch to Original Medicare + Medigap — they can only do so during specific enrollment windows. Missing these windows means waiting until the next one, potentially months away.

The Three Windows for Leaving Medicare Advantage

Annual Enrollment Period (AEP): October 15 – December 7. Your parent can switch to a different Medicare Advantage plan or drop Medicare Advantage entirely and return to Original Medicare. Changes take effect January 1.

Medicare Advantage Open Enrollment Period (MA OEP): January 1 – March 31. If your parent is currently enrolled in a Medicare Advantage plan, they can switch to a different MA plan or disenroll from Medicare Advantage and return to Original Medicare. They can also add a standalone Part D plan if returning to Original Medicare. Changes take effect the first of the following month. This window is only available to people already in Medicare Advantage — it cannot be used to join MA for the first time.

Special Election Periods (SEPs). Certain qualifying events allow changes outside the standard windows:

• Plan leaving the service area or terminating its CMS contract
• Parent moves out of the plan's service area
• Loss of employer or union coverage
• Qualifying for Medicaid or Extra Help (LIS)
• Parent is enrolled in a low-performing plan rated below 3 stars for the last 3 years (this SEP allows a switch to another Medicare Advantage or drug plan)
• The Medicare Plan Finder provided incorrect plan information that influenced enrollment

When Your Parent's Plan Is Leaving Their Area

Each fall, Medicare Advantage plans notify CMS whether they'll continue operating in each county for the following year. If a plan is exiting your parent's area, they'll receive a non-renewal notice (the Annual Notice of Change, or ANOC) by September 30.

This triggers an automatic Special Election Period. Your parent can:

1. Switch to another Medicare Advantage plan available in their county during the AEP (October 15–December 7)
2. Return to Original Medicare and apply for a Medigap policy — with guaranteed-issue rights because the plan termination is a qualifying event

The guaranteed-issue protection is time-limited: the Medigap application window can open 60 days before coverage ends and closes no later than 63 days after the plan termination date. Don't wait until after the plan ends to start the Medigap application.

What Happens When You Disenroll

When your parent disenrolls from Medicare Advantage, they automatically return to Original Medicare (Parts A and B). For a Medicare Advantage Open Enrollment Period change, Original Medicare starts the first day of the following month; Annual Enrollment Period changes take effect January 1.

Original Medicare has no drug coverage, so your parent needs to separately enroll in a standalone Part D prescription drug plan to avoid the late enrollment penalty that accumulates for every month without creditable drug coverage. This can be done simultaneously with the MA disenrollment.

If your parent wants a Medigap policy to cover Original Medicare's deductibles and coinsurance, they should apply during a guaranteed-issue window. Simply disenrolling from MA during the AEP or OEP does not automatically trigger guaranteed-issue Medigap rights — those rights depend on specific qualifying events (plan termination, trial rights) or state-level protections.

The Annual Notice of Change: What to Watch For

Even if your parent's plan isn't leaving, the ANOC (mailed by September 30) may reveal changes that matter:

• Higher out-of-pocket maximum — the plan may raise its cap closer to the $9,250 CMS limit
• Narrower formulary — your parent's medications may move to a higher cost-sharing tier or be removed entirely
• Provider network changes — doctors or hospitals may have left the network
• New or expanded prior authorization requirements
• Reduced supplemental benefits — dental, vision, or hearing coverage may shrink

If the ANOC shows significant benefit reductions, the AEP (October 15–December 7) is the window to switch plans or return to Original Medicare.

Making the Transition Smooth

Timing matters. If your parent is disenrolling during the MA OEP (January–March) to return to Original Medicare:

1. Submit the disenrollment through medicare.gov, 1-800-MEDICARE, or the plan directly
2. Apply for a standalone Part D plan immediately
3. If a guaranteed-issue Medigap window applies, submit the Medigap application before the 63-day deadline expires
4. Confirm Original Medicare coverage is active before canceling any other interim coverage

The Medigap vs Medicare Advantage coverage decision guide includes an enrollment timeline planner to coordinate these overlapping deadlines.

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