The Internal Revenue Service has told Vole it must front up to $28.9 billion.

Microsoft said the dispute concerns the company’s allocated profits between countries and jurisdictions between 2004 and 2013. It said up to $10 billion in taxes that the company has already paid are not reflected in the proposed adjustments made by the IRS.

Microsoft plans to contest the notices through the IRS’ administrative appeal and is willing to go to judicial proceedings if necessary.

“Microsoft disagrees with these proposed adjustments and will pursue an appeal within the IRS, a process expected to take several years,” the company said in its filing. “We believe we have always followed the IRS’s rules and paid the taxes we owe in the U.S. and worldwide.”

Microsoft said that as of Sept. 30, 2023, its allowances for income tax contingencies were adequate.