What is a Medigap plan?
A Medigap plan — also called Medicare Supplement Insurance — is a private policy that helps pay some of the health care costs Original Medicare does not cover, like copayments, coinsurance, and deductibles. Medigap works only with Original Medicare, not with Medicare Advantage.
What it means
- Medigap plans are standardized by letter (A, B, C, D, F, G, K, L, M, N) so the same lettered plan has the same benefits across insurers.
- You pay the Medigap insurer a monthly premium in addition to your Part B premium.
- The best time to buy is during your 6-month Medigap Open Enrollment Period, when insurers cannot deny you or charge more due to health.
Action steps
- Enroll in Part B — your Medigap Open Enrollment Period starts the month it begins.
- Compare the lettered plans at medicare.gov, then get quotes from multiple insurers for the same letter.
Risks & deadlines
- Your Medigap Open Enrollment Period lasts only 6 months; outside it, insurers can typically use medical underwriting.
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Last verified: 2026-07-18
- We do not offer every plan available in your area. Please contact Medicare.gov, 1-800-MEDICARE, or your local State Health Insurance Assistance Program (SHIP) to get information on all of your options.
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