You can switch from Medicare Advantage to Original Medicare during Medicare's October 15–December 7 Open Enrollment, but that does not automatically guarantee a Medigap policy. Your right to buy Medigap depends on your Part B enrollment, qualifying trial or guaranteed-issue rights, and state rules. Check those protections before making a coverage change.
Leaving Medicare Advantage for Original Medicare during annual Open Enrollment does not automatically guarantee that you can buy Medicare Supplement Insurance (Medigap). This matters if you expect Medigap to help cover out-of-pocket costs. Medicare explains the health-plan switch, while its Medigap guidance describes the separate buying rights.
Two enrollment decisions have different rules
Fall Medicare Open Enrollment runs October 15 through December 7. A plan change requested during fall 2026 generally starts January 1, 2027. When leaving Medicare Advantage, you may need a separate Part D prescription drug plan. Medigap supplements Original Medicare, but cannot pay Medicare Advantage expenses. The fall election window is not a general new six-month Medigap buying window.
When must an insurer offer Medigap?
Medicare’s federal Medigap guidance says the one-time six-month Medigap Open Enrollment Period begins on the first day of the month when you are 65 or older and enrolled in Part B. After that period, an insurer may be allowed to ask medical questions, charge more or deny an application unless another guaranteed-issue right or state protection applies.
Compare two hypothetical people. Someone age 65 who just enrolled in Part B may still be in the six-month federal window. Someone age 70 who has had Part B for five years and has no special protection may face medical underwriting. Both might have the right to leave Medicare Advantage in the fall, but they do not necessarily have the same right to purchase Medigap.
Check trial rights and state exceptions
A federal trial right may apply to a person who joined Medicare Advantage when first eligible at 65 and returns to Original Medicare within the first year. A Medicare Advantage plan leaving Medicare or other qualifying coverage losses may also create guaranteed-issue rights. The available policies and application windows depend on the event. Some states give more generous rights than federal law. Use Medicare’s Medigap eligibility questions and contact your state insurance department before relying on an exception.
January through March does not guarantee Medigap
The official 2027 Medicare handbook says someone already in Medicare Advantage can switch to another Medicare Advantage plan or return to Original Medicare between January 1 and March 31, 2027. That is a health-plan election window, not an automatic Medigap guaranteed-issue period. Confirm supplement availability and separate prescription coverage before making a January switch.
Already own Medigap? Do not assume you can get it back
If you have Medigap and are considering Medicare Advantage, do not assume you can buy the same supplement again later. Medicare’s policy-switching guidance warns that getting Medigap back is often not guaranteed. A Medigap policy you keep cannot pay Medicare Advantage copayments, deductibles, coinsurance or premiums. Check federal trial rights and state protections before cancellation.
A safer sequence before December 7
First, determine whether you are within the Medigap Open Enrollment Period or have a trial, guaranteed-issue or state right. Second, ask the insurer whether it will issue a policy, what it costs, and when coverage can begin. Third, compare doctors, prescription coverage, Part B costs, any Part D and Medigap premiums, and expected out-of-pocket expenses against your existing Medicare Advantage plan. Only then complete any fall health-plan change by December 7.
For broader costs, read our 2027 Medicare cost comparison. If your Medicare Advantage plan is ending, see the plan-termination guide because additional rights may apply.
Prepared with AI assistance using Medicare sources checked November 14, 2026. The scenarios are hypothetical and the featured image is an original editorial illustration.
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