1. Under Medicare Secondary Payer guidelines, this is a group health plan that covers (a) employees of either a single employer or employee organization that employed at least 100 full-time or part-time employees on 50% or more of its regular business days during the previous calendar year or (b) two or more employers or employee organizations, at least one of which employed at least 100 full-time or part-time employees on 50% or more of its regular business days during the previous calendar year. It includes individual policies (including Medigap policies) purchased by or through an employer or former employer of the individual or family member. 2. Employer-sponsored group health plan that gives insurance coverage for 20 or more employees and is primary to Medicare. This number of employees varies depending on each state’s regulations.