“The U.K. and the U.S. are both among the biggest enablers and the biggest losers of this lose-lose tax system,” said the chief executive of the Tax Justice Network.

A study published Tuesday estimates that tax dodging enabled by the United States, the United Kingdom, and other wealthy nations is costing countries around the world nearly half a trillion dollars in revenue each year, underscoring the urgent need for global reforms to prevent rich individuals and large corporations from shirking their obligations.