The United States tax code will never be accused of being simple or easy to comprehend. With a tangle of exceptions and loopholes, individuals and corporations can work their way around paying their full income tax rate with ease.According to The Detroit News, General Motors continues to avoid paying its federal income taxes since the company exited bankruptcy. In 2008, the Treasury Department ruled that the automaker could use $18 billion in losses from "old" GM to offset any profits. That means from a tax perspective, GM still hasn't earned enough money to overcome its losses. The automaker has raked in more than $13 billion since 2009.Of course, GM isn't the only company dodging the federal income tax. Ford , for example, payed $268 million in worldwide income taxes last year, despite claiming an income of $7.8 billion. Likewise, since Chrysler Group, LLC. is a limited-liability partnership, it isn't required to pay federal income taxes. According to The Detroit News, very few companies pay the full 35 percent federal corporate income tax rate.But that doesn't mean GM or other companies get off entirely. GM says it pays considerable state taxes, and the company reports that its global tax rate for 2012 may jump to 12 or 13 percent, up from an earlier estimate of 10 percent.