Earlier this month, EU regulators fined Microsoft 280.5 million euros ($356 million) for defying a 2004 antitrust ruling requiring it to share key information on its office servers with rivals, and warned the company to comply or face bigger daily fines from next month.
The information is needed so rivals' servers could compete on a level playing field with Microsoft's own. Microsoft must help its rivals interconnect smoothly with Windows.
Part of the decision was based on the evaluation of an independent monitoring trustee, British Professor Neil Barrett, who was nominated by the U.S. software giant.
The non-compliance penalty imposed on July 12 was the first of its kind and came on top of a record 497 million euro fine the Commission levied in its landmark antitrust decision against Microsoft in March 2004.
That decision found that the company abused the dominance of its Windows operating system to squeeze out competitors.
Microsoft faces a further fine of up to 3 million euros a day if it found to be still not in compliance with the ruling.
The move signaled the Commission's determination to force the software giant to obey its order. The company had two years to comply and used legal and court procedures to spin out the process.
Microsoft says it has made massive efforts to comply with the Commission's ruling and had 300 people working to complete its package of interoperability information.
The company, which has appealed against every ruling against it so far by the Commission, has said it will appeal against the non-compliance fine.