A service bureau refers to any company that offers its services to other companies. The services offered allow other companies to outsource non-essential business functions that the service bureau might be able to do better anyway, freeing up resources that can then be used for the core business functions.

The most common service bureaus today are call centers or customer care centers to whom many large service companies now outsource some of their operations, as the former may be able to do the job better because they already have the necessary infrastructure and expertise. Banks are also another service bureau being used by companies to handle payroll and employee benefits such as car/housing loans.