»The German Implementation of the Authorised OECD Approach: Taxation of Permanent Establishments in Sec. 1 Foreign Transaction Act (AStG)«: The work starts with an overview how permanent establishments were treated in DTAs historically since the League of Nations' Model Tax Convention and the Caroll report. Moreover, the AOA is evaluated against the background of economic standards. The taxation of permanent establishments under Sec. 1 German Foreign Transaction Act (AStG) is closely examined, in particular the relevance of OECD documents for the interpretation, the elements of the provision and the treatment of partnerships.