[JURIST] GlaxoSmithKline (GSK) [corporate website] has agreed to pay $3.4 billion [IRS press release] to settle Internal Revenue Service [official website] claims in what the IRS calls "the largest tax dispute in the history of the Internal Revenue Service." According to the IRS:

The agreement between GSK and the IRS brings to a conclusion a dispute dating back to the 1980s and involves adjustments to GSK's tax years from 1989 through 2000. The Tax Court case concerns "transfer pricing," an accounting method requiring that related parties engage in transactions at arm's length to ensure the proper reporting of taxable income. GSK and the IRS have also reached agreement for tax years 2001 through 2005 with respect to the transfer pricing issues arising in those years.

The Tax Court dispute for years 1989-2000 involves intercompany transactions between GSK and certain of its foreign affiliates relating to various GSK "heritage" pharmaceutical products. Specifically at issue is the level of U.S. profits reported by GSK after making intercompany payments that took into account product intangibles developed by and trademarks owned by its U.K. parent, and other activities outside the U.S., and the value of GSK's marketing and other contributions in the U.S. Under the settlement agreement, GSK has conceded over 60% of the total amount put in issue by the two parties for the years pending in Tax Court.

In addition to the $3.4 billion payment, GSK has agreed to abandon its efforts to receive a $1.8 billion refund, also related to the transfer pricing dispute.

According to a GSK press release Monday, the final net cash cost to the company will be about $3.1 billion, taking into account federal, state and local taxes, interest and also the benefit of tax relief on the payments made. AP has more.