Medicare Supplement plans, also called Medigap, fill the gaps in Original Medicare so you face fewer surprise bills. This guide explains every standardized plan, what they cost, and how to choose.
What is a Medicare Supplement (Medigap) plan?
A Medicare Supplement plan is private insurance that pays your share of costs under Original Medicare (Part A and Part B), such as the 20% coinsurance Medicare doesn't cover, hospital deductibles, and coinsurance. Medigap works alongside Original Medicare, not in place of it. Because plans are federally standardized, a Plan G from one insurer covers exactly the same benefits as a Plan G from another, what changes is the monthly premium and the company's service. Medigap lets you see any doctor or hospital in the U.S. that accepts Medicare, with no networks and no referrals. To compare plans available where you live, call 1-800-MEDIGAP (1-800-633-4427).
What are the 10 standardized Medigap plans?
Medigap is sold in 10 standardized plans, lettered A, B, C, D, F, G, K, L, M, and N. Each letter offers a fixed set of benefits set by federal law, so the only differences between insurers are price and reputation. Plans F and G offer the most comprehensive coverage, with Plan G being the top choice for people new to Medicare (Plan F is closed to those who became eligible on or after January 1, 2020). Plan N offers strong coverage at a lower premium with small copays. High-deductible versions of Plan G and Plan F trade lower premiums for a higher annual deductible. Massachusetts, Minnesota, and Wisconsin standardize their plans differently.
How much do Medicare Supplement plans cost in 2026?
Medigap premiums vary widely by plan letter, your age, ZIP code, gender, tobacco use, and the insurer, typically ranging from roughly $90 to $300+ per month for Plan G. Two people with identical coverage can pay very different amounts depending on the carrier, which is why comparison shopping matters. Premiums also rise over time based on how the plan is rated: community-rated, issue-age-rated, or attained-age-rated. Beyond premium, your only Plan G cost is the annual Part B deductible ($257 in 2025; the 2026 figure is set by CMS each fall). A licensed agent at 1-800-MEDIGAP can compare every carrier in your area at no cost so you don't overpay for identical benefits.
When can you enroll in Medigap?
The best time to buy is your Medigap Open Enrollment Period, the six months that begin the first month you're 65 or older AND enrolled in Part B. During this window you have guaranteed issue rights: insurers must sell you any plan they offer, at their best rate, regardless of health. Miss it and you may face medical underwriting, where carriers can charge more or decline you for pre-existing conditions, except in limited guaranteed-issue situations. There's no annual Medigap enrollment season like Medicare Advantage, you can apply any time, but approval outside your open enrollment isn't guaranteed. Don't risk losing your one-time guaranteed window; call 1-800-MEDIGAP to confirm your dates.
Medigap vs. Medicare Advantage: which is right for you?
Medigap and Medicare Advantage are different ways to get Medicare coverage, and you can't use both at once. Medigap pairs with Original Medicare and a standalone Part D drug plan, offering nationwide doctor access, no networks, and predictable costs, but a monthly premium. Medicare Advantage (Part C) often has $0 premiums and bundles extras like dental and vision, but uses networks, requires referrals or prior authorizations, and charges copays as you use care. Frequent travelers, people who want freedom to choose specialists, and those who prefer budgeting a fixed premium often favor Medigap. The right answer depends on your health, budget, and providers, our agents explain the trade-offs free at 1-800-MEDIGAP.