As corporate lobbyists seek to preserve business tax breaks and cut the corporate tax rate, the Government Accountability Office said big companies with earnings paid just 12.6 percent of their worldwide income in taxes in 2010.
The GAO report came at a time of tight government budgets and increased attention among lawmakers to corporate tax avoidance in Europe and the United States.
While U.S. companies often complain about the 35 percent top tax rate being among the world's highest, "what they don't like to admit is that hardly any of them pay anything close to it," said Senator Carl Levin, a Michigan Democrat, in a statement.
The GAO report - which did not name specific companies - said that earlier studies had found U.S. companies paid 20 percent to 30 percent of their income in taxes.
But the GAO said public financial statements and new IRS data showed the tax rate for profitable corporations was even lower.
Levin released a report in May detailing corporate tax avoidance by Apple Inc (AAPL.O). Last year, he scrutinized Microsoft Corp's (MSFT.O) low tax bills.
Democratic President Barack Obama and some lawmakers have called for lowering the top 35 percent corporate tax rate.
In April, GAO published a report saying the annual cost of corporate tax breaks to the U.S. Treasury has more than doubled to $180 billion since 1987.
