Cost allocation is a process of attributing cost to particular cost centers. For example the wage of the driver of the purchasing department can be allocated to the purchasing department cost center. It is not necessary to share the wage cost over several different cost centers. Cost and services are not identical to each other.

Cost allocation is the assigning of a common cost to several cost objects. For example, a company might allocate or assign the cost of an expensive computer system to the three main areas of the company that use the system. A company with only one electric meter might allocate the electricity bill to several departments in the company.

Allocation implies that the assigning of the cost is somewhat arbitrary. Some people describe the allocation as the spreading of cost, because of the arbitrary nature of the allocation. Efforts have been made over the years to improve the bases for allocation. In manufacturing, the overhead allocations have moved from plant-wide rates to departmental rates, from direct labor hours to machine hours to activity based costing. The goal is to allocate or assign the costs based on the root causes of the common costs instead of merely spreading the costs.