The 50 biggest US companies are among those that Oxfam claim have shifted 1.6 trillion dollars (1.5 trillion euros) to offshore accounts otherwise known as "tax havens."
The report was released by the organization ahead of meetings on Monday between the International Monetary Fund and the World Bank in the US capital.
"Tax avoidance has become standard business practice across the globe. Corporate tax dodgers cheat America out of approximately $135 billion in unpaid tax revenues every year," said a senior advisor to Oxfam, Robbie Silverman.
Big names involved
The study highlights Apple, Microsoft and Wal-Mart as three examples of leading US corporations that are parking money outside of the United States. Oxfam says Apple, at the top of the rankings, has shifted $200 billion offshore.
In the United States, the tax rate for corporations is normally 35 percent at the federal level. As part of his campaign to loosen the strings on tax regulations, US President Donald Trump proposed a cut in the tax rate to 15 per cent. Companies are permitted to store profits from international operations in order to avoid such taxes.
A further $200 billion was shifted to so-called "tax havens" in 2015, which is comparable with the annual economic output of Canada, according to the study, which cites Oxfam's own data.
"In the case of international corporations, tax avoidance is now a popular sport," added Oxfam's tax expert Tobias Hauschild.
rd/hg (dpa, AFP)