GlaxoSmithKline, IRS in Dispute Over Taxes

British drug maker GlaxoSmithKline is disputing Internal Revenue Service allegations that it improperly avoided a significant portion of the U.S. taxes on billions of dollars in sales of some drugs.

The maker of the heartburn drug Zantac and other blockbusters hasn’t been formally charged by the IRS. The agency also hasn’t said how much the company might owe. IRS and British tax agency representatives have been trying to resolve the issue, the company said.

The IRS alleged that Glaxo’s U.S. subsidiary, GlaxoSmithKline Holdings (Americas) Inc., overpaid its European parent for the drugs, thereby artificially reducing its U.S. profit--and taxes--from 1989 through 1999.

Glaxo’s shares fell $1.89 to $39.12 on the New York Stock Exchange.