Drug giant (NYSE: GSK) is involved in a $1.9 billion fight with the Internal revenue Service, the Wall Street Journal

GSK, which maintains its U.S. headquarters in RTP and employs some 5,000 people across the region, may owe “back taxes, interest and penalties stemming from tax deductions Glaxo generated essentially by making payments to itself,” according to the newspaper.

The Journal said the IRS dispute is focused on “a practice known as earnings stripping, in which a multinational company reduces its taxes by claiming interest deductions for payments to a related unit overseas. The company claims deductions on its U.S. tax return, but no money ultimately leaves the parent company’s coffers, and publicly reported profit is unchanged.”

Reuters also has about the dispute.