Medicare supplemental health insurance, called “Medigap,” is meant to provide coverage for the things that Medicare doesn’t cover. To qualify for Medigap, you must be enrolled in Medicare Part A and Medicare Part B. Your Medigap coverage will help cover excess costs, such as co-insurance costs for stays in the hospital or a nursing facility, and even the deductibles in your Part A and Part B Medicare plans. You can find this plan through private insurers and organizations that cater to the elderly. Costs will vary according to coverage.