Materials Costs. In job order costing, materials requisitions are the basis for charging direct materials to specific jobs. In process costing, the details are reduced because materials are charged to departments rather than to jobs, and there are only a few departments using materials. Materials requisition forms may be useful for control of materials. If the requisitions are not priced individually, the cost of materials used can be determined at the end of the production period through aperiodic inventory approach-that is, adding purchases to beginning inventory and deducting ending inventory.