What is required, Professor Amparo Grau proclaims in this extremely well-thought-out book, is adequate regulation of mutual assistance for the recovery of tax claims. It is essential to "internationalize" the link between the power to levy taxes and the power to actually enforce them. In international relations as currently established, the most promising way to achieve effective enforcement in the recovery of tax claims is through the mechanism of mutual assistance – an administrative function that tends to become mired in highly complex webs of procedure. Mutual Assistance for the Recovery of Tax Claims offers an in-depth analysis of the potential powers and necessary limits of the mutual assistance function at the national administrative level. This entails close examination of the issues that so often turn out to be the most problematic, such as whether or not claims enforced through mutual assistance merit priority and the validity of the foreign authority's right to enforce. This detailed investigation alone, with its clear highlighting of the crucial challenges, would be enough to make this book enormously valuable; but Professor Amparo Grau goes further by offering recommendations that contribute to the strengthening and effectiveness of mutual assistance procedures. She also considers the growing role of multilateral treaties in the field, and even envisions the possibility of an international fiscal court.