What Does Medigap Do? 
A Medicare supplement -LRB- Medigap -RRB- insurance , sold by private companies , can help pay some of the health care costs that Original Medicare does n't cover , like copayments , coinsurance , and deductibles . Some Medigap policies also offer coverage for services that Original Medicare does n't cover , like medical care when you travel outside the U.S. . If you have Original Medicare and you buy a Medigap policy , Medicare will pay its share of the Medicare-approved amount for covered health care costs . Then your Medigap policy pays its share . A Medigap policy is different from a Medicare Advantage Plan . Those plans are ways to get Medicare benefits , while a Medigap policy only supplements your Original Medicare benefits . Medigap policies do n't cover everything ! Medigap policies generally do n't cover WEBSITELINK long-term care , vision or dental care , hearing aids , eyeglasses , or private-duty nursing . 