The legal action is being brought by Mark McLaren – a former parliamentary and legal affairs manager at consumer group Which?.
The claim is against Barratt Redrow, Bellway, The Berkeley Group, Bloor Homes, Persimmon, Taylor Wimpey, and Vistry Group, including its Countryside Partnerships division.
More than 700,000 people who bought new-build homes in Great Britain between October 2015 and June 24 this year are covered.
The claim is now heading to the Competition Appeal Tribunal for the go-ahead.
The case alleges buyers paid over the odds for their homes.
The reason, it is claimed, is that major builders shared commercially sensitive information with each other instead of competing fairly – pushing prices up artificially.
It follows a probe by the Competition and Markets Authority (CMA).
The watchdog investigated whether the firms swapped sensitive data for around two years up until February 2024 – including pricing details, the number of property viewings and buyer incentives such as upgraded kitchens or stamp duty contributions.
Rather than face further action, the builders agreed to pay £100million into affordable housing programmes.
They also made binding commitments to stop sharing information.
The CMA did not rule on whether competition law had actually been broken.
Mr McLaren is represented by competition law firms Geradin Partners and Hausfeld.
He believes each affected homeowner could be owed between £3,100 and £6,200 – totalling between £2.2billion and £4.5billion.
Mr McLaren said: “Buying a home is one of the biggest financial commitments most of us will make.
“If, as seems to be the case, housebuilders shared sensitive pricing and sales information with one another instead of competing properly, homeowners across Great Britain may well have been left out of pocket as a result.
“This claim is about standing up for those buyers and ensuring that compensation is delivered to those who deserve it.”
Scott Campbell, a partner at Hausfeld, said: “For most homeowners, bringing an individual claim simply isn’t realistic, as the cost and complexity put it out of reach.
“That’s why this collective action is so important.
“It provides a practical route for hundreds of thousands of consumers to seek compensation where they may otherwise have had no way of doing so.”
The housebuilders have been approached for comment.
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