"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 straightforward. 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."
CRS Report for Congress, R43568
Federation of American Scientists: http://www.fas.org/sgp/crs/index.html