Most U.S. and foreign corporations don’t pay federal income tax, according to a study by the Government Accountability Office, which analyzed data from the Internal Revenue Service from 1998 to 2005, MSNBC reported.

According to the report, two-thirds of U.S. corporations paid no federal income tax and 68 percent of foreign companies doing business in the United States avoided corporate taxes. Collectively the companies studied had $2.5 trillion in sales. About 25 percent of the U.S. corporations not paying corporate taxes were considered large corporations, with assets of at least $250 million or $50 million in receipts.

The study did not investigate why companies weren’t paying federal income or corporate taxes but suggested that it could be because of operating losses or tax credits. The report did not name any company specifically.