The Treasury issued a series of warnings ahead of the referendum, and now Tory Brexiteer Charlie Elphicke is calling for a probe.
Elphicke, who sits on the Public Accounts Committee, said the bleak scenarios had not come to pass, arguing the Treasury must face scrutiny.
“The people of Britain need a Treasury with robust processes to ensure that forecasts are accurate, objective and can be trusted,” Elphicke wrote.
Treasury figures were based on an immediate triggering of Article 50, and policy makers failing to respond to the Brexit verdict.
A Treasury spokesman said: “We want the best outcome for Britain. That means pursuing a bespoke arrangement, which was not what the Treasury’s pre-referendum analysis was based on.”
It comes after Cambridge academics last week questioned the Treasury’s Brexit warnings.