This thesis deals with the utilization of foreign losses within cross-border groups. It explains the requirements for the integration of foreign entities as group members, the calculation of losses and the conversion to Austrian tax law. The main part of this thesis deals with the subsequent taxation within group membership and when leaving it. In addition it is investigated whether the cross-border utilization of losses goes conform with European law. Finally, based on the definition of abuse in § 22 BAO and the jurisdiction of the European Court of Justice, the limits between legal tax planning and abuse are illustrated.