Eligibility requirements determine who can purchase Medigap policies. Here’s a breakdown of the eligibility criteria:  1. Enrolled in Original Medicare (Part A and Part B)  2. Age 65 or Older  3. Under 65 with a Disability or End-Stage Renal Disease (ESRD)  4. Medigap Enrollment Periods 5. Cannot Have a Medicare Advantage Plan  6. Residency Requirements If you are unsure if you are eligible for medicare supplement insurance contact a trusted insurance agency.