This article discusses the revised mutual agreement and arbitration procedure in Art. 25 of the Germany–US tax treaty. Following an explanation of the appeal, equity and consultation procedures, which remain unchanged, the article critically examines the new mandatory arbitration clause. Potential interpretation and application problems are highlighted, as well as possible solutions. In this context the Memorandum of Understanding (including the operating guidelines for the Arbitration Board) of 8 December 2008 is considered.