The bachelor's thesis discusses the topic of aggressive tax planning at the EU level. The theoretical part of the thesis first briefly introduces the topic of development of individual initiatives in the fight against aggressive tax planning at the EU or OECD level. Furthermore, this section also slightly discusses the BEPS project, from which the EU drew in part when developing its own rules. Subsequently, the theoretical part of the thesis deals with the very introduction of the ATAD directive, in which emphasis is placed on the explanation and presentation of all introduced rules. Following the ATAD directive, the form in which this directive has been implemented into Czech tax legislation is presented at the very end of the theoretical ...