The incidence of international tax evasion and tax avoidance is growing rapidly, due in great part to the enormous increase in electronic trading. Although international tax harmonization - particularly in the European Community legal system - has made great strides, it has failed to keep pace with the even more rapid and vigorous manoeuvres of tax evaders (unlawful) and tax avoiders (lawful) as they engender ever more massive losses of revenue. What is required, Professor Amparo Grau proclaims in this 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.