How or where do you purchase Medigap supplemental coverage?

Supplemental Medigap plans are sold by private insurance companies. Medicare.gov has a tool to help you find one in your area, but you must purchase Medigap plans directly from the insurer. In most states, you’ll find that Medigap policies are named by letters (ex: Medigap Plan F or Medigap Plan G). If you live in Massachusetts, Minnesota, or Wisconsin, Medigap plans have different names that are not letter-based.