The digital services taxes that some countries plan to levy on U.S. tech companies’ revenue could violate U.S. tax treaties, a Treasury official said.

“We actually believe that under most of our treaties, the DST would be a covered tax, so imposing it on a U.S. company would violate the treaty,” said Lafayette “Chip” Harter, deputy assistant secretary of international tax affairs at the Treasury Department. He was speaking April 11 at an American Bar Association International Law event in Washington.

A number of countries are moving ahead with unilateral measures to tax the revenue large companies make...