Use of a Predetermined overhead Rate
overhead costs are charged to all work done during any period. The problem is how to a charge. It is possible to allocate actual overhead to all work completed during the month. if production volume is steady from month to month and overhead costs are incurred in level monthly amounts, this method results in a reasonable charge to production each period Typically. however, large variations do occur between months or between seasons of the year, which would cause work completed during diferent months to receive significantly different charges for overhead. For example, unreasonable product cost are calculated if the actual cost of repairs are charged immediately and directly to jobs or product. ordinarily repairs are necessary because of wear and tear over long periods. further, during months when significant repair work is done, it is often necessary to slow or stop production temporarily while repairs are carried out. The resulting high repair cost and low production volume results in astronomical unit cost calculations if actual (high) overhead is charged to actual (Low) production in those months. Because several components of overhead cost are incurred in the same pattern as that described for repairs, and because overhead cost needs to be assigned promptly to production, overhead generally is charged to production at predetermined amounts, not at actual amounts incurred Because of the impossibility of tracing overhead to specific jobs or specific products. overhead cost is allocated across jobs and units. A predetermined overhead rate permits a consistent and logical allocation to each unit of output. in both job order and process cost accumulation. predetermined overhead rates provide the only feasible method of computing product overhead costs promptly enough to serve management's need for product cost information, to identify inefficiencies, and to smooth out the illogical month-to-month fluctuations that would otherwise appear in reported unit cost.
Departmentalization of factory overhead means dividing the plant into segments, called departments, to which overhead costs are charged. For accounting purposes, dividing a