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The Medigap underwriting trap when you switch back
Medicare Advantage plans cannot refuse you for health reasons. Medigap insurers generally can, except in protected periods. Here is who is protected, for how long, and how to check before you drop a plan.
The trap in one paragraph
You join a Medicare Advantage plan. Years later you want to return to Original Medicare, perhaps because of the network or prior authorization. To limit your risk in Original Medicare, which has no out-of-pocket limit on its own, you would want a Medigap policy. But outside a few protected windows, federal law allows Medigap insurers to use medical underwriting: they can deny you or charge you more because of your health. KFF notes this contrasts with Medicare Advantage and ACA Marketplace plans, which cannot deny coverage for pre-existing conditions.
How big is the risk?
KFF analysis of 2023 data found that nearly three quarters (74%, about 20.9 million people) of Medicare Advantage enrollees had a medical condition that could result in a Medigap denial. KFF's list of conditions that insurers' applications may treat as grounds for denial includes, among others, diabetes with complications, coronary artery disease, chronic kidney disease, COPD, heart failure, cancers such as breast and prostate, stroke, Parkinson's disease and Alzheimer's disease. Insurers can also decline applicants for recent hospital stays or home health use, or for pending recommendations such as testing or surgery that has not happened yet.
What underwriting looks like
- A health questionnaire, and increasingly a check of your prescription history. A Milliman actuary quoted by KFF Health News said that prescription history may be the primary driver of a decision.
- Higher premiums or a waiting period of up to six months for pre-existing conditions in certain circumstances.
- Different insurers have different rules, so one denial does not mean every company will say no. A SHIP counselor can often point to companies that accept a given diagnosis.
Who is protected
- The Medicare Advantage trial right. If you joined Medicare Advantage when first eligible for Medicare at 65 and leave within the first 12 months, you can buy any Medigap policy sold in your state. If you dropped Medigap to join Medicare Advantage for the first time, you can return within 12 months and get the same policy back if the company still sells it.
- Your plan leaves or you move. If your plan stops covering your area, its contract ends, or you move out of its service area, you have guaranteed-issue rights. Apply up to 60 days before your coverage ends and up to 63 days after.
- Your state. Connecticut, Massachusetts and New York guarantee Medigap year-round; Maine, Delaware, Rhode Island and Minnesota have limited annual windows; many states have "birthday rules" for people who already have Medigap. See state by state.
The full federal list is on the guaranteed issue rights page.
Why timing matters
Annual Open Enrollment (October 15 to December 7) and the Medicare Advantage Open Enrollment Period (January 1 to March 31) let you leave a Medicare Advantage plan for Original Medicare. They do not, by themselves, guarantee you a Medigap policy. A Medigap policy also cannot start until your Medicare Advantage coverage ends. Before you disenroll, find out whether you would be accepted. If you leave and are declined, you could be in Original Medicare with no supplement and no yearly cap, and you may have to wait for another enrollment period to change again.
Sources
- KFF: Medigap Guaranteed Issue Requirements: An Overview of Federal and State Rules (Oct 13, 2026)
- KFF Health News: In Switching to Original Medicare, Beware of Medigap Plan Refusals (Mar 16, 2026)
- Medicare.gov: Choosing a Medigap Policy (PDF)
- Medicare.gov: How Medigap works
- Medicare.gov: Joining a plan
- SHIP National Technical Assistance Center: find your State Health Insurance Assistance Program
Common questions
Can a Medigap company really turn me down?
Yes, outside your 6-month Medigap Open Enrollment Period and the guaranteed-issue situations, federal law lets insurers use medical underwriting to deny a policy or charge more. A few states, such as Connecticut, Massachusetts and New York, require year-round guaranteed issue.
Does Annual Open Enrollment guarantee I can get Medigap?
No. It lets you change between Medicare Advantage and Original Medicare, but Medigap acceptance depends on a guaranteed-issue right or on underwriting.
What if I have been in Medicare Advantage for years?
You are generally outside the 12-month trial right. Check whether your state has a year-round or annual guaranteed-issue rule, whether a qualifying event applies (such as your plan leaving your area), and talk to a SHIP counselor about insurers that may accept you.