International law of taxation is a very dynamic discipline, and a book such as this is just a snapshot of the current international tax regime. The goal of this book is to provide the reader with insights on how the international tax regime is embedded in a broader context in the international law regime. The focus of this book, therefore, is on the interaction of the international tax law regime with other legal regimes, such as the international trade law or the investment law regime. Moreover, this book outlines the main elements of the European Union (EU) tax system. Of course, besides these cross-disciplinary areas, this book discusses the functioning of double tax treaties as the main legal sources of the international tax regime. The more recently crafted treaty-based rules of the international tax regime, such as the mutual exchange provisions in various international treaties, are also discussed. This book can and should serve as a course book for a course on international tax law. Depending on how such course is structured, the entire book or large parts of it may be of interest to the students. The book should also serve as a go-to source for practitioners. It is of course impossible to cover all the topics pertinent to the international tax regime in a comprehensive way, but no major area has been left out. Moreover, case law from around the world are referred to and discussed rather than approaching the topic with reference only to a specific jurisdiction.