This Nutshell, which provides an introduction to U.S. international taxation useful to both U.S. and non-U.S. students and practitioners interested in the topic, has been revised and updated with the most up-to-date discussion of recent regulatory guidance interpreting the significant changes to the U.S. international tax rules introduced by the 2017 tax act. It also includes a discussion of how the newly enacted U.S. book minimum tax interacts with the international tax rules. Referenced throughout are the global tax developments of recent years and how those rules and proposals interact with the U.S. international tax regime. In addition to providing a survey of the technical rules, the book also offers insight into tax planning considerations and how these have been impacted by U.S. and global developments. Both the U.S. activities of foreign taxpayers, as well as the foreign activities of U.S. taxpayers are explored. In today's world, it is crucial for those involved in business and investment activities to understand the tax consequences of cross-border flows. The author's career spans the academic and private sectors, and she has used her experiences to distill the complexities of real-world tax considerations into a clearly written, straight-forward presentation of the key international tax concepts.