The Canada-United States Tax Treaty is the most important tax treaty for Canada and certainly the most complex tax treaty in the world. The reasons are obvious: the United States is Canada’s largest trading partner and the treaty links two of the world’s most complex income tax systems. Furthermore, the range of economic contacts between Canada and the United States is far more extensive than is commonly found between tax treaty partners. The result is an agreement of extraordinary intricacy that frequently gives rise to unusual and subtle interpretative issues.

A solid understanding of the Canada-United States Tax Treaty is essential to any practitioner who advises clients on cross-border transactions. This entails not only an understanding the text of the treaty provisions, but also the multiple sources of interpretative guidance and the products of an active jurisprudence on both sides of the border. Full appreciation of the Treaty’s provisions also requires at least some familiarity with the relevant domestic laws of each of the countries. Such familiarity is not easily obtained because both countries produce vast bodies of materials dealing with cross-border transactions, and these materials are in a more or less constant state of evolution and development.

The authors of this loose-leaf volume provide an extremely useful service to the tax community by commenting on the most important articles of the Canada-US Tax Treaty from the point of view of each of the Treaty’s partners. Following a brief introduction, each chapter of the service tracks an important article of the Treaty. There is a discussion in each chapter of both Canadian and U.S. domestic laws and interpretations of the Treaty. Relevant primary materials, including the various jointly agreed U.S. Treasury Department Technical Explanations of the Treaty and its Protocols, are included for ease of reference.

The service will be an excellent place to begin research on individual international tax rules that arise in the context of the Treaty. Similarities and differences between Canadian and American tax laws are easy to identify when the rules of domestic law are presented in the same structure and order. Many of the key issues are discussed in a detailed manner so that a reader in either country will be able to grasp, at least at an initial level, the rules at play in the other country. Important sources of case law, statutory provisions, and administrative policies are cited for those who wish to pursue further study of particular issues. Overall, this service fills a real need and, beyond being a helpful source on issues of immediate interest to tax advisors and students, has the potential of furthering general understanding of the tax and treaty policies of Canada and the United States.

We congratulate the authors on the publication of this impressive volume.