It hasn't worked out as planned. Companies have found ways around the law that create new rewards for executives. When Actavis Inc. changed its incorporation to Ireland in October, the New Jersey-based drugmaker helped CEO Paul Bisaro avoid the law's bite by handing him more than $40 million of stock as much as three years ahead of its schedule, then promising him an additional $5 million to remain with the company.

The payouts to executives highlight the ineffectiveness of the 2004 law, which contained a series of provisions aimed at reducing the tax benefits of reincorporating overseas. In the past two years, a fresh wave of companies has fled the U.S. system to avoid hundreds of millions of dollars in taxes.

The 2004 law has "clearly been a failure" in halting the tax exodus, said Edward Kleinbard, a professor at University of Southern California's Gould School of Law. "And it now has the perverse result of putting money into executives' pockets sooner."