Medigap is a health insurance policy designed by private companies to help senior citizens pay for health costs not covered by Medicare (i.e., "fill in the gap"). There are 12 different "standardized" Medigap policies available to seniors, labeled A-L. Each offers a different set of costs and benefits, based upon the specific needs of potential customers. The benefits and costs of these individual plans will be the same, regardless of which insurance company offers them. By law, and for the protection of seniors, a Medigap policy must be clearly identified as a "Medicare Supplement Insurance." In order to be eligible for a Medigap plan, potential participants must be enrolled in Medicare Part A and Part B. Medigap policies are only available to individuals; in other words, a husband and wife each have to purchase their own Medigap plan. It is not uncommon for private companies to provide Medigap policies to their retirees.