American companies that reincorporate abroad are not doing so to avoid paying taxes on U.S. earnings, despite the often misleading impressions left by the rantings of Senators Carl Levin, Dick Durbin, Elizabeth Warren, and others to the contrary. They are doing it to avoid paying U.S. taxes on earnings in other countries.
The United States is the only industrialized nation that uses a “worldwide” tax system, in which a U.S.-based corporation must pay taxes to our government regardless of where the corporation earns its money. Most of the rest of the world uses a “territorial” tax system, in which a corporation pays taxes only where it earns income.
via Abusive Tax Policies Are to Blame for Corporations Going Overseas | Heartlander Magazine.