Microsoft faces $28.9B back tax bill from IRS after profit allocation audit; plans appeal

IRS claims Microsoft owes $28.9 billion in back taxes, penalties and interest from 2004-2013 audit.
Dispute centers on Microsoft's allocation of profits between countries and jurisdictions.
Microsoft plans to appeal IRS decision, expects process to take several years.
Microsoft argues it has followed all rules and regulations on taxes.
IRS audit did not account for potential $10B tax reduction from 2017 tax law changes.