Medigap insurance policies are sold by private companies and help cover some of the "gaps" in Medicare programs. The costs for these policies are not covered by Medicare: You must pay for this supplemental coverage.

A Medigap policy can help cover expenses, such as deductibles and co-payments. However, they no longer cover prescription drugs, since those costs now are covered, in part, by the new Medicare Part D program. (Note: If you have been receiving Medicare benefits for a while, you may have an older Medigap policy that does offer coverage for prescriptions.)

In most states, you can choose from as many as 12 different types of Medigap policies, also known as plans A through L. The plans differ based on the extra benefits they provide. Insurance companies cannot offer different benefits from one another. They can offer only standardized Medigap plans, although they choose which ones to sell or not to sell. This makes it easier for you to compare coverages.

Generally, when you buy a Medigap policy you must have Medicare Part A and Part B. In addition, you and your spouse must each purchase separate Medigap policies, since one policy can’t cover you both.

To decide if you need a Medigap policy, download "Choosing a Medigap Policy: A Guide to Health Insurance for People with Medicare" from the Medicare site, or ask your Health Mart pharmacist for advice.

Also, check out AARP’s guide, "5 Steps to Buying a Medigap Policy."