The article focuses on possible financial effects of the transformation towards Gold Open Access publishing based on article processing charges and studies an aspect that has so far been overlooked: Do possible cost sharing models lead to the same overall expenses or do they result in different financial burdens for the research institutions involved? It takes the current state of Gold OA publishing as a starting point, develops five possible models of attributing costs based on different author roles, number of authors and author-address-combinations. The analysis of the distributional effects of the application of the different models shows that all models result in similar expenditures for the overwhelming majority of institutions. Still, there are some research institutions where the difference between most and least expensive model results in a considerable amount of money. Given that the model calculation only considers publications that are Open Access and where all authors come from Germany, it is likely that different cost sharing models will become an issue in the debate on how to shoulder a possible large scale transformation towards Open Access based on publication fees.