Buchner, StefanRiehle, Dirk2021-12-242021-12-242022-01-04978-0-9981331-5-7http://hdl.handle.net/10125/80238A key part of taxation, controlling, and management of international collaborative programming workflows is determining the costs of a supplied software artifact. The OECD suggests the use of the Cost Plus method for calculating these costs. However, in the past, this method has been implemented using only coarse-grain data from the costs of whole organizational units. Due to the move to inner source software development, we need a much more fine-grain solution for computing the detailed time spent on programming specific components. This is necessary, because a more accurate work time distribution is required to fulfill the fiscal and administrative challenges posed by collaborating across organizational boundaries. In this article, we present a novel method to determine the time spent on an individual code contribution (commit) to a software component for use within cost calculation, especially for taxation purposes. We demonstrate the usefulness of our approach by application to a real-world data set gathered at a large multi-national corporation. We evaluate our work through feedback received from this corporation and from the German Ministry of Finance.10 pagesengAttribution-NonCommercial-NoDerivatives 4.0 InternationalCo-Development with Software and Business Engineering Frameworks and Methodsclient-supplier relationshipcommit transaction historycost plus methodinner sourcetransfer pricingtext10.24251/HICSS.2022.896