What is Medicare Supplement or "Medigap"?

Medicare Supplement Insurance, or "Medigap," is extra coverage you can purchase from a private insurer to help pay for costs not covered by Original Medicare. Medigap policies are standardized by federal regulations and are typically labeled with letters (Plan A through Plan N) in most states. The benefits for each plan are the same across all insurers, but prices may vary.

You have a 6-month "Medigap Open Enrollment" period that begins the first month you have Medicare Part B and are 65 or older. During this time, you can enroll in any Medigap plan, and insurers cannot deny you coverage or charge higher premiums based on pre-existing health conditions. After this period, it may be more difficult or expensive to buy a Medigap policy. While you can apply for a Medigap policy at any time, after the Open Enrollment period, you will be subject to underwriting based on your health and any pre-existing conditions. This may either disqualify you from coverage or result in higher premiums.