»Branch of Activity Requirement Under the German Reorganisation Tax Act in Theory and Practice«: In the absence of Supreme Court clarification of essential aspects of interpretation regarding the branch of activity requirement under the German Reorganisation Tax Act, the taxpayer is in practice forced to rely on possibly unlawful administrative guidance and to obtain a binding ruling from the tax authorities. This work analyses the lack of legal certainty in reorganisations involving separate business units and develops practical solutions to mitigate tax risks in this respect.