A Medigap policy is an insurance policy that helps supplement Original Medicare and is sold by private companies. A Medigiap policy can help pay some of the remaining health care costs that Original Medicare doesn't pay for covered services and supplies, like copayments, coinsurance, and deductibles.
Original Medicare pays for much, but not all, of the cost for covered health care services and supplies. These are “gaps” in Medicare coverage.
If you have Original Medicare and a Medigap policy, Medicare will pay its share of the Medicare‐approved amounts for covered health care costs. Then your Medigap policy pays its share. A Medigap policy is different from a Medicare Advantage Plan (like an HMO or PPO) because those plans are ways to get Medicare benefits, while a Medigap policy only supplements the costs of your Original Medicare benefits.
Note: Medicare doesn’t pay any of your costs for a Medigap policy.
All Medigap policies must follow federal and state laws designed to protect you, and policies must be clearly identified as “Medicare Supplement Insurance.” Each standardized Medigap policy must offer the same basic benefits, no matter which insurance company sells it.