Medicare Supplements: sometimes called “Medigap” insurance, help pay for the things traditional Medicare doesn’t. Medicare Supplemental Plans are standardized and are identified in most states by letters. Although the plans are standardized (as an example, a plan F will always have the same benefits), insurance carriers can charge different rates for these plans, so it can be helpful to shop around. If you live in Massachusetts, Minnesota or Wisconsin, Medigap plans are standardized in a different way.