A report by accounting firm PricewaterhouseCoopers found that the
average effective three-year corporate tax rate for U.S. based
corporations rose to 26.3 percent, up 0.7 percent from the previous
year. The effective tax rate is the tax rate after expenses and tax
offsets.
http://www3.cfo.com/article/2012/5/tax_tax-incentives-effective-tax-rate-