Ignoring these interactions and allocating support costs directly to producing departments may produce unfair and inaccurate cost assignments. For example, Power, although a support department, may use 30 percent of the services of the Maintenance Department. The maintenance costs caused by Power Department belong to the Power Department. By not assigning these costs to the Power Department, its costs are understated. In effect, some of the costs caused by Power are hidden in the Maintenance Department because maintenance cost would be lower if the Power Department did not exist. As a result, a producing department that is a heavy user of power and average or below-average user of maintenance may then receive, under the direct method, a cost allocation that is understated.