For more than ten years there was a heavy dispute within the OECD as to whether in cross-border supply of staff the user of the workers becomes the (“economic”) employer so that with short-term foreign assignments (not exceeding 183 days) the right of taxation relating to the workers goes to the user country. Germany was in the camp of these countries. Austria, however, was in the opposite camp, because as long as neither the wording nor the context of a tax treaty requires a specific understanding of a term used in the treaty (in this case: “employer”) the principle of Art 3 para 2 of the treaties mandatorily requires domestic law to be relevant. Under Austrian domestic law, it is the supplier and not the user of the personnel who is treated as the employer. In the 2010 update of the OECD Model Tax Convention the dispute was brought to an end by concluding that a tax treaty is not capable of allowing an autonomous interpretation of that term so that domestic law is relevant. In the Austro-German tax treaty of 2000 this dispute should have been “buried” independently from the OECD developments by virtue of a special clause proposed by the German negotiator. Unfortunately, it was a ...