Variant costing is the use of surcharge rates can lead to considerable distortions in the costing of product variants (costing, process-oriented). The process-oriented calculation provides results that are appropriate to the cause. It can be useful to define dependency relationships in the cost center. If the process quantities for activity-quantity-induced processes were determined, for example, either by the number of products and variants or by the quantity volume for which the cost center is responsible, the percentage of the planned process quantity that arises depending on the volume or variant would have to be estimated for each process.
The product cost portion of each process would then be as follows (Process cost accounting): The volume-dependent process costs (planned process quantity x volume-dependent portion x process cost rate) are to be divided by the total volume. The variant-dependent process costs (planned process quantity x variant-dependent portion x process cost rate) must first be divided by the number of variants and the costs determined in this way, then divided by the respective volume of each variant. If the variant and quantity structure changes, the number of volume or variant-dependent processes must be determined again.
When determining product costs, the product cost shares of all processes are added to the individual costs and machine costs determined as known. It often turns out that products with small quantities are burdened with significantly higher indirect costs according to the process costing than with the Surcharge calculation. In addition to the quantity and number of variants, other main influencing variables for the occurrence of indirect costs can of course be defined. The type of dependency relationships must always be selected in such a way that a causal allocation of costs and thus the determination of decision-relevant costs is possible.