In 2002, Microsoft purchased Navision from the Danish firm Navision A/S for around $1.3 billion. Navision was later turned into Microsoft Business Solutions, one of the most profitable parts of the Microsoft empire. Shortly after Microsoft purchased Navision, they moved the legal rights to Ireland in an attempt to cut down on tax expenditure.
A report by Danish news outlet, DR Forsiden, has shown that Microsoft could be asked by the Danish government for up to $1 billion in tax from the Navision deal. Lars Kiertzner, a professor at the Copenhagen Business School and an expert on accounting, described the case as "remarkable", before saying it's "definitely one of the biggest [they've] seen."
Source: Neowin