Medicare is a nationwide health insurance program for individuals aged 65 and over and certain disabled individuals. The basic Medicare benefit package provides broad protection against the costs of many, primarily acute, health care services. However, Medicare beneficiaries may still have significant additional costs, including co-payments, coinsurance, deductibles, and the full cost of services that are not covered by Medicare. In 2008, about 17% of Medicare beneficiaries purchased the private supplemental insurance known as Medigap to fill some of the cost gaps left by Original Medicare. This book provides an overview of Medigap insurance with a focus on the history of Medigap legislation; the various types of Medigap plans; consumer protections awarded to Medigap beneficiaries; and the requirements facing the insurance providers and the National Association of Insurance Carriers (NAIC).