The 2006 protocol to the 1989 tax treaty and protocol between Germany and the United States amended both the treaty and the protocol. The 2006 protocol provides for mandatory arbitration if certain conditions are satisfied. In December 2008, the competent authorities of Germany and the United States signed a Memorandum of Understanding which deals with requests for competent authority assistance and arbitration. The Memorandum of Understanding is published in I.R.S. Announcement 2008-124, and guidelines supplementing the Memorandum of Understanding are published in I.R.S. Announcement 2008-125. This article provides an overview of the substantive and procedural provisions for mandatory arbitration in the 2006 protocol and the Memorandum of Understanding.