A Medigap policy is health insurance sold by private insurance companies to fill the “gaps” in Original Medicare Plan coverage. Medigap policies help pay some of the health care costs that the Original Medicare Plan doesn't cover. If you are in the Original Medicare Plan and have a Medigap policy, then Medicare and your Medigap policy will each pay its share of covered health care costs.

Generally, when you buy a Medigap policy you must have Medicare Part A and Part B. You will have to pay the monthly Medicare Part B premium. In addition, you will have to pay a premium to the Medigap insurance company. As long as you pay your premium, your Medigap policy is guaranteed renewable. This means it is automatically renewed each year. Your coverage will continue year after year as long as you pay your premium. In some states, insurance companies may refuse to renew a Medigap policy bought before 1992.

Insurance companies can only sell you a “standardized” Medigap policy. Medigap policies must follow Federal and state laws. These laws protect you. The front of a 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 provide the same benefits. Generally, the only difference between Medigap policies sold by different insurance companies is the cost.

You and your spouse must buy separate Medigap policies. Your Medigap policy won't cover any health care costs for your spouse.

Some Medigap policies also cover other extra benefits that aren't covered by Medicare.

You are guaranteed the right to buy a Medigap policy under certain circumstances.