1. Employer or employee organization (union) or both that establishes and maintains an employee benefit plan (e.g., includes government health plans and church health plans). 2. In a 401(k) defined-contribution pension plan, an employer. 3. Under the Health Insurance Portability and Accountability Act (HIPAA), either an employer in case of an employee benefit plan, employee organization in case of a plan maintained by an employee organization, or if two or more employers, the association or committee that maintains the plan.