[Excerpt] The U.S. corporate income tax is based on worldwide economic activity. If all of a corporation’s economic activity is in the United States, then tax administration and compliance is relatively straight-forward. Many corporations, however, operate in several jurisdictions, which creates complications for tax administration and compliance. Further, corporations may actively choose where and how to organize to reduce their U.S. and worldwide tax liabilities. Some of these strategies have been referred to as expatriation, inversions, and mergers. This report examines them in light of recent expansion of their use and growing congressional interest. This report begins with a brief discussion of relevant portions of the U.S. corporate income tax system before examining how inversions were commonly structured. The report then looks at how Congress and Department of the Treasury have reduced the benefits of inversions. The report concludes with an examination of methods that remain to invert and policy options available to prevent or limit these inversions.