For controlling purposes, it is necessary to keep track of services, their costs, and who has received them. Cost accounting usually investigates which costs incur (cost-type accounting), where costs incur (cost center accounting), and for what activities or services costs incur (cost unit accounting). According to the accounting purpose, the time period to be observed and the scope of the costs to be accounted have to be defined. The results of cost accounting , that is, KPIs , serve as input for controlling @en