U.S. President Barack Obama speaks during swearing-in ceremonies on the West front of the U.S Capitol in Washington, January 21, 2013.   REUTERS/Kevin Lamarque (UNITED STATES  - Tags: POLITICS)
The latest corporate tax dodge to hit the news is the practice of inversions, big corporations either merging with other corporations or buying a company and then claiming that they are based in that country, thereby avoiding paying corporate taxes in the U.S. The Joint Commission on Taxation has estimated that the U.S. could lose as much as $19.5 billion in tax receipts in the next decade because of this growing practice. Senate Democrats have introduced the Stop Corporate Inversions Act to curtail the practice, but recognize that this legislation isn't going anywhere fast in this Congress. 

So Sens. Dick Durbin, Elizabeth Warren, and Jack Reed have written to President Obama, asking him act on his own on the issue.
“The coming flood of corporate inversions justifies immediate executive action,” says the letter, spearheaded by Senator Richard J. Durbin of Illinois, the No. 2 Democrat, and signed by Elizabeth Warren of Massachusetts and Jack Reed of Rhode Island. […]
Treasury Secretary Jacob J. Lew said at a conference in New York last month that he did not believe he had the power to act alone on the issue. But Mr. Obama recently delivered a speech decrying inversions, and administration officials had been evaluating the legality of unilaterally limiting them.
“They’re looking at what they can do on their own,” Senator Charles E. Schumer, Democrat of New York, said in an interview last week. “They want to do it. The president really dislikes the inversions, and if they feel they have a strong legal ability to do it, they will.”

The practice is increasing, with two large pharmaceutical companies and a national drug store chain (giant AbbVie, based in Illinois, Pennsylvania generic manufacturer Mylan, and Walgreens) all either just moving overseas or threatening to. President Obama focused on the issue in a speech last month in Los Angeles, saying, "I don’t care if it's legal. It's wrong. […] You shouldn't get to call yourself an American company only when you want a handout from the American taxpayers."
One of the Obama administration's former Treasury officials, Stephen Shay, thinks that it is within the President's power to act on this unilaterally under existing tax law. Three U.S. senators agree.
N.B. Walgreens buckled under massive outpouring from patriotic Americans.  Staying in USA.