Medigap plans, also known as Medicare Supplement Insurance, work in conjunction with Original Medicare (Part A and Part B) to help cover costs that Medicare doesn't fully pay for. Basic Process: 1. Receive Care: Visit a healthcare provider or use medical services. 2. Medicare Pays First: Medicare Part A and/or Part B covers a portion of the approved amount. 3. Medigap Pays Second: Your Medigap plan covers the remaining costs like copayments, coinsurance, and deductibles.