A Medigap policy is health insurance sold by private insurance companies to fill the "gaps”, or uncovered procedures or benefits provided by the Original Medicare Plan. Medigap coverage policies help to pay some of the health care costs that the Original Medicare Plan doesn't cover. If you have an Original Medicare Plan and have a Medigap policy, then your Medicare and Medigap policies will each pay a portion of the covered health care costs. Generally, when you buy a Medigap policy you must have Medicare Part A and Part B. You will also have to pay a premium to the Medigap insurance company.

The Medigap policy has a guaranteed to be renewed as long as you make your payments of the monthly premium. This means it is automatically renewed each year. This guarantee of renewability creates a sense of faith in users of the Medigap insurance. Be aware that in some states, insurance companies may refuse to renew a Medigap policy bought before 1992. Insurance companies have only certain options and will only sell you a "standardized" Medigap policy. Federal and state laws regarding Medigap policies must be complied with. These laws are for the clients protection. The front page of any Medigap policy must clearly identify it as "Medicare Supplement Insurance." It's important to compare Medigap policies, because costs can vary. The standardized Medigap policies that insurance companies offer must generally provide the same benefits. Cost will be the main difference between Medigap policies sold by different insurance companies.