What was the 2013 federal corporate tax rate in the United States?

The 2013 U.S. corporate tax rates ranged from 15 percent to 35 percent, notes the Tax Foundation. The 35 percent rate applies to earnings above $18,333,333.

In 2013, tax rates were 15 percent on a corporation's first $50,000 of income, 25 percent on the next $25,000, 34 percent on the next $25,000 and 39 percent on the next $235,000 according to the Tax Foundation. The tax rate was then 34 percent on the next $9,665,000, 35 percent on the following $5,000,000, 38 percent on the next $3,333,333 and 35 percent on all additional income. These rates remained unchanged as of 2014.