A group of employees that are treated as employees of a single employer for certain employee benefit requirements under the Internal Revenue Code (IRC) and the Employee Retirement Income Security Act of 1974 (ERISA).

An affiliated service group consists of a service organization (meaning an organization, the principal business of which is the performance of services) and one or more organizations related to the service organization through ownership or a working relationship.

By arranging the ownership of related business entities in an artificial manner, the controlled group rules under ERISA could be avoided. The affiliated service group rules were enacted to prevent the avoidance of these rules by expanding the controlled group to separate but affiliated entities.