A new Government Accountability Office report showed that one in five big companies don’t pay any income taxes, according to CNN Money.

CNN Money reported that the GAO’s analysis found that before 2012, 24 percent of profitable large corporations owed no income tax in 2011, 22 percent owed nothing in 2010 and 21 percent owed nothing in 2009.

The analysis said that many of the reasons corporations owed no income tax were because of tax deductions for losses in previous years, depreciating assets that they were able to write off, and offshore profits that haven’t been brought back to the United States.

Of the large corporations that did have to pay income taxes that year, they owed a total of $268 billion.

In the years between 2008-2012, large corporations paid only 22 percent of their income in U.S. corporate income taxes after foreign, state, local taxes were included, a figure well below the 35 percent top corporate income tax rate.

Just in the past year, 27 companies on the Standard & Poor’s 500 paid nothing in income taxes, USA Today reported.

Some of these companies included Level 3 Communications, United Continental Airlines, and General Motors.

United Continental reported a $3.2 billion income tax credit in 2015 despite reporting pre-tax earnings of $4.2 billion. Due to the $4.7 billion in allowances they claimed because of losses in previous years, they erased their $1.5 billion tax bill.

Level 3 Communications got a tax credit of $3.2 billion in 2015 despite reporting a pre-tax profit of $283 million in the same year because of credits associated with losses at their own company and a company they acquired in 2014.

General Motors got a tax credit of of $1.9 billion, even though its earnings before taxes hit $7.7 billion. The company reported a federal income tax expense of $1 billion, but the tax bill became a credit due to a tax break the company got in connection with General Motors Europe.

The U.S. Treasury recently released a set of guidelines that were intended to crack down on companies that try to reduce their tax bills by merging with foreign companies, CNN Money reported.