Medicare Parts A & B cover many medical supplies and services, but they dont pay for all health care costs. Some people decide to buy Medigap policies to fill in the coverage gaps. Medigap policies are supplemental insurance policies sold by private insurers to help beneficiaries pay the coinsurance, copays, and deductibles associated with Medicare Parts A & B. Some Medigap policies also cover additional services, such as emergency medical care while traveling overseas, or prescription drugs. People who choose to buy Medigap policies must pay a monthly premium to the private insurance company that sold them the policy.
The Basics of Medigap
In order to be eligible to buy a Medigap policy, you must already have Medicare Parts A & B. You will have to pay the Medicare Part B premium in addition to the premium for your Medigap policy.
Medigap policies are standardized. The federal government has established 12 different types of plans, labeled A through L. Private insurers in every state except Massachusetts, Minnesota, or Wisconsin can sell any, all, or none of these standardized Medigap policies. This site offers a convenient chart showing what each of the different standardized plans covers.
If you live in Massachusetts, Minnesota, or Wisconsin, you will have different plans to choose from. People living in these states should contact their states Department of Insurance to find out what types of Medigap policies they can buy.
It is important to shop around for a Medigap policy. The plan benefits are standardized, but the premiums are not. One company may offer Plan A for $70/month, while another could offer Plan A for $60.

