Medicare Supplement Insurance (Medigap) coverage is health insurance that helps cover some costs Original Medicare does not cover, such as coinsurance, copayments, and deductibles.

Private insurance firms sell Medigap policies. Some Medigap policies additionally cover benefits that Original Medicare does not, such as emergency international travel fees. Other types of health coverage, such as Medicare Advantage Plans (such as HMOs or PPOs), standalone Medicare Prescription Drug Plans, employer/union group health coverage, Medicaid, or TRICARE, do not pay your share of the costs. If you have Medicaid or a Medicare Advantage Plan, insurance providers are often unable to sell you a Medigap policy.