The intersection between fiscal state aid and taxation has become more topical than ever. Mounting financial crises have left EU Member States scrambling to increase their tax revenue, balance their budgets, and attract capital. Taking advantage of these trends, multinational enterprises have lobbied for favourable tax arrangements, raising questions about the breadth of control the Commission can and should practise. To address egregious instances of favourable taxation, the Commission has tried to simultaneously use soft law and deploy Treaty rules on state aid. Fiscal State Aid Law and Harmful Tax Competition in the EU examines the use of state aid rules against national tax measures. Kyriazis's book presents a targeted investigation of these measures in two parts. The first part addresses Commission decisions and ECJ judgments of the early 2000s, which the author calls the "first wave". The second part consists of all the recent Commission decisions and investigations into tax schemes and individual tax rulings, most notably the Apple, Fiat, Starbucks, and Amazon investigations, which Kyriazis labels the "second wave". The characteristics and common threads of each wave are set out, their similarities and differences dissected, and their nexus to the EU's fight against harmful tax competition explored. Containing a thorough analysis of the legal concept of fiscal state aid under Article 107(1) of the Treaty on the Functioning of the European Union, this book will be of interest to scholars of European and International Tax law and practitioners working in the field of European competition law.