While healthcare reform kept the U.S. House and Senate busy last year, legislators are expected to take up the issue of corporate taxes this year, and companies are wary of the changes to international tax rules proposed by the Obama administration last year.

"The Obama proposal is extraordinarily stressful for U.S. multinationals," says Joan Arnold, chair of the tax practice group at Pepper Hamilton in Philadelphia. "It will significantly complicate the ability to operate in a tax-efficient manner."

Companies' biggest concerns involve the so-called deferral rules. The administration wants companies to hold off taking deductions related to offshore earnings until those earnings have been repatriated and taxed.