What is Medigap?

What a Medigap policy does

Original Medicare pays its part of a covered bill and leaves the rest to you: deductibles, coinsurance and copayments, with no yearly limit. A Medigap policy is extra insurance, sold by private companies, that pays some or all of that remaining share. It works only alongside Original Medicare, so you need Part A and Part B to buy one, and you keep paying your Part B premium.

Each policy covers one person. Married couples who both want Medigap buy two policies.

The lettered plans

Medigap policies are standardized and named by letter. In most of the country there are 10 types: Plans A through D, F, G, and K through N. A plan with a given letter has the same basic benefits no matter which company sells it, so the price is the only difference between two companies' versions of the same letter. Three states standardize their policies in a different way, and in some states you may be able to buy a variant called Medicare SELECT. Not every plan is offered everywhere.

What Medigap does not cover

The timing that matters most

You get one Medigap Open Enrollment Period, lasting 6 months. It starts the first month you have Part B and are 65 or older, and it does not come back each year. During those months, a company must sell you any policy it offers, cannot turn you down or charge you more because of your health, and cannot make you wait for coverage except for a pre-existing condition. After it ends, a company may use medical underwriting, which can mean a higher price, fewer choices, or a refusal.

In certain situations later on, a company cannot deny you a policy; Medicare calls these Medigap protections, and your state may give you more rights. If you are under 65 and have Medicare because of a disability, federal law generally does not require companies to sell you a policy, though in some states companies do offer one. For how this choice compares with an all-in-one plan, see Medicare Advantage vs Medigap.

Keeping your policy

Standardized policies renew automatically each year, even if your health changes. The company can end your policy only if you stop paying the premium, you were untruthful on your application, or the company itself fails. Premiums vary with the plan, where you live and other factors, and they can change from year to year.

Common questions

Last reviewed October 2026. Medicare rules, dates and dollar amounts can change each year; Medicare.gov has the official details.