This guide helps people with Medicare understand Medigap (also called "Medicare Supplement Insurance") policies. A Medigap policy is health insurance sold by private insurance companies to fill gaps in Original Medicare coverage. Medigap policies can help pay your share (coinsurance, copayments, or deductibles) of the costs of Medicare-covered services. Some Medigap policies also cover certain benefits Original Medicare doesn't cover. Medigap policies don't cover your share of the costs under other types of health coverage, including Medicare Advantage Plans, stand-alone Medicare Prescription Drug Plans, employer/union group health coverage, Medicaid, Department of Veterans Affairs (VA) benefits, or TRICARE. Insurance companies generally can't sell you a Medigap policy if you have coverage through Medicaid or a Medicare Advantage Plan. Also available in Spanish.