Balfour Beatty, Bam Construct, Laing OвЂ™Rourke, Skanska and Sir Robert McAlpine are the firms who have been invited to tender.
They have until early October to submit first stage tenders, with a winner to be announced in August 2010.
The scheme will be built on the site of the former national hockey stadium, which is being demolished, near Milton Keynes Central railway station.
Network Rail will submit a planning application for the 40,000m2 development in early November. The offices are scheduled to open in 2012.
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