Medicare Supplement Insurance, also known as Medigap, is private insurance that helps cover costs not paid by Original Medicare, such as copayments, coinsurance, and deductibles. It works alongside Medicare Parts A and B, allowing you to reduce out-of-pocket expenses for medical services. Medigap policies are standardized and offer different levels of coverage, ensuring predictable costs. These plans do not include prescription drug coverage, so a separate Part D plan may be needed. Medigap provides flexibility, letting you see any doctor nationwide who accepts Medicare, and offers peace of mind by filling gaps in your healthcare coverage.