This thesis deals with the group taxation according to section 9 of the Austrian Corporation Tax Act. The group taxation breaks through the principle of individual taxation and it usually reduces the tax burden for the group leader and whose group members as long as beside the profits are losses too. Therefore, in the first part of the thesis the group taxation will be explained in general. Furthermore, there is to be found a detailed description of how earnings are assigned and on which stage the individual results of the group members will be balanced. In addition, there were some significant changes due to the Tax Amendment Act 2014 concerning the group taxation. Consequently, the main part takes a close look at the current legal position. Due to the frequent involvement of foreign group members, the increased duty to cooperate as well as the administrative assistance are very important. In the area of administrative assistance, the legal basis and possible methods will be explained. Though the possibilities for investigations in foreign countries are very limited, the increased duty to cooperate and the limits in this context is mentioned in the last part of the thesis.