The specialized book "European Legal Limits of Size Differentiation in Tax Law" offers an in-depth analysis of the complex interactions between national tax sovereignty and the rules of the European internal market. The author highlights the challenges that arise from tax differentiation based on company sizes. In particular, it examines to what extent a systematic additional burden on larger companies compared to smaller ones can be interpreted as a violation of fundamental freedoms or as prohibited state aid. By considering various doctrinal approaches, a comprehensive understanding of the legal framework is established. The book is aimed at professionals in the field of tax law as well as students who wish to engage with the legal aspects of corporate taxation in the European context.