Medigap policies supplement (not replace) traditional Medicare insurance. They can help pay your share of costs like coinsurance, copayments, or deductibles of Medicare-covered services that Original Medicare doesn’t cover. Some Medigap policies also cover certain benefits Original Medicare doesn’t cover like emergency foreign travel expenses. In other words, it fills the “gaps” in your coverage.
When you make a claim, your Original Medicare policy covers its share of the costs since it is primary. The Medigap policy then covers its share since it is secondary. You are responsible for the difference. Medicare doesn’t help pay for the cost of your Medigap policy.