Supply chain and production processes optimise overhead areas, i.e. non-direct cost areas, not material or labour costs, which are the focus of manufacturing cost calculation. Rather, the optimisation of indirect areas is in the foreground, which are hidden in the surcharge rates in a classic manufacturing cost evaluation. Many process optimisation projects fail to determine cost savings. Therefore, various approaches to determining process costs are described so that the profitability of process improvements can be determined. A focus is the presentation of different concepts for process cost accounting suitable for various tasks.