As a group, the 288 corporations (profitable Fortune 500 companies) paid an effective federal income tax rate of 19.4 percent over the five-year period, 2008-2012.
The statutory, and often sited, 35% is not a reality for the majority of profitable companies. Though the tax breaks vary widely, as does the rate actually paid. “Tax reform”that strikes at tax breaks will have a difficult time running the gambit of dark money, lobbyists, PACs and wealthy contributors.
Source:
http://www.ctj.org/corporatetaxdodgers/sorrystateofcorptaxes.pdf