Can I Switch from Medicare Advantage to Medigap?

You can disenroll from Medicare Advantage during the Annual Enrollment Period (October 15–December 7) or the Medicare Advantage Open Enrollment Period (January 1–March 31) and return to Original Medicare. That part is straightforward. The hard part is buying a Medigap policy afterward — because in most states, you'll face medical underwriting.

Here's what that means in practice, and the specific windows where underwriting doesn't apply.

Why Switching Is Harder Than Joining

When your parent was 65 or older and enrolled in Part B, they had a six-month Medigap Open Enrollment Period with guaranteed-issue rights. They could enroll in any Medigap policy sold in their state regardless of health.

That federal protection is one-time. Once it closes, the default rule in most states is that Medigap insurers can review your parent's medical history, charge higher premiums for pre-existing conditions, or deny the application entirely.

This creates the central problem: the parents who most want to leave Medicare Advantage — those who've developed serious health conditions and are frustrated with prior authorization denials — are the ones least likely to pass underwriting for a Medigap policy.

Guaranteed-Issue Windows for Switching

Federal law carves out specific situations where Medigap insurers must sell a policy without medical underwriting. These are the windows that matter for someone leaving Medicare Advantage:

Trial Right 1 — First-time MA enrollee at 65. If your parent enrolled in Medicare Advantage when they first turned 65 (Parts A, B, and MA all starting simultaneously), they have 12 months to change their mind. Within that window, they can disenroll from MA, return to Original Medicare, and buy any Medigap plan from any insurer on a guaranteed-issue basis. The Medigap application must be submitted no later than 63 days after the MA plan terminates.

Trial Right 2 — Dropped Medigap to try MA. If your parent already had a Medigap policy, dropped it to try Medicare Advantage for the first time, and decides within 12 months it isn't working, they can return to their previous Medigap plan with the same insurer. If that plan is no longer sold, they can buy Plan A, B, D, G, K, or L from any insurer. The window runs from 60 days before the MA plan ends to 63 days after.

Plan leaving the service area. If the Medicare Advantage plan exits your parent's county or terminates its CMS contract entirely, guaranteed-issue rights kick in. Your parent can purchase Medigap Plan A, B, D, G, K, or L without underwriting from 60 days before coverage ends through 63 days after it ends.

Loss of other coverage. If your parent loses employer group health insurance or retiree coverage, they get a 63-day guaranteed-issue window.

For federal guaranteed-issue windows, the deadlines are rigid. Missing the applicable deadline ends the guaranteed-issue right, so the insurer is not required to accept the application without medical underwriting.

State Protections Beyond Federal Law

Federal guaranteed-issue rights cover specific triggering events. But fifteen states have birthday-rule protections in 2026 (New Mexico joins in 2027), creating annual switching windows for existing Medigap policyholders, and five states mandate continuous guaranteed issue year-round:

Continuous guaranteed issue (any time, any reason): Connecticut, Massachusetts, Maine, New York, Vermont. Your parent can switch from Medicare Advantage to Medigap at any point without medical underwriting.

Birthday-rule states (annual window around the birthday): California (60 days from birth month), Delaware, Idaho, Illinois (ages 65–75 only, same carrier), Indiana, Kentucky, Louisiana (same carrier), Maryland (30 days), Nevada, Oklahoma (active policy; maximum 90-day gap), Oregon, Utah (same carrier), Virginia, West Virginia (same carrier or affiliate unless unavailable; 24-month holding period), Wyoming. New Mexico joins in January 2027.

These birthday-rule windows typically allow switching to a plan of equal or lesser benefits — so a move from Medicare Advantage to Medigap Plan G would require first establishing the Medigap policy during a guaranteed-issue period, then using the birthday rule for future plan changes.

The Practical Switching Process

If your parent has a guaranteed-issue right or lives in a continuous-guarantee state:

1. During the applicable enrollment period — the Medicare Advantage Open Enrollment Period (January 1–March 31), Annual Enrollment Period (October 15–December 7), or a qualifying Special Election Period — disenroll from Medicare Advantage through medicare.gov or by calling 1-800-MEDICARE
2. If you use the Annual Enrollment Period, Original Medicare starts January 1; if you use the Medicare Advantage Open Enrollment Period, it starts the first day of the following month
3. Apply for Medigap within the relevant guaranteed-issue window — don't wait until after the MA plan ends
4. Simultaneously enroll in a standalone Part D prescription drug plan (Medigap does not cover prescriptions)

If no guaranteed-issue window applies, your parent can still apply for Medigap — the insurer just isn't required to accept them. Some insurers are more lenient than others, and some health conditions trigger denial while others don't. A SHIP counselor (free, unbiased Medicare counseling through every state) can help identify which local insurers have the most favorable underwriting practices.

When to Stay on Medicare Advantage

Switching makes the most sense when your parent's health needs have outgrown the plan's network or prior authorization hurdles. But if your parent is generally satisfied with their plan's providers and hasn't hit significant care denials, switching introduces costs (higher Medigap premiums, separate Part D plan) that may not be worth it.

The decision framework is in our coverage decision guide, which includes a cost-comparison worksheet and a state-by-state switching rules reference — built specifically for adult children managing this transition for a parent.

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