A PEO or co-employment arrangement involves all or a significant number of the client’s existing worksite employees in a long-term, non-project related, employment relationship. The PEO brings services to the client, including the management of human resources, employee benefits, payroll and workers’ compensation. The PEO assumes employer responsibility for employment tax, benefit plans and other human resource purposes. If a PEO relationship is terminated, the co-employees will cease to work for the PEO but will continue as employees of the client.

By comparison, a leasing or staffing service supplies new workers on a temporary or project-specific basis. These leased employees return to the staffing service for reassignment after completion of their work with the client company. Some would define employee leasing as a supplemental, temporary employment arrangement where one or more workers are assigned to a customer for a fixed period of time, often for a specific project. This concept creates little long-term equity or investment between the worker and customer.