The outspoken Tory backbencher raised the issue after spotting figures in Budget documents from the Office for Budget Responsibility (OBR) outlining an “own resources contribution” to Brussels in 2022 and 2023.
Speaking during the Budget debate, Jacob Rees-Mogg said: “This is rather like spotting an error in Wisden Cricketers’ Almanack, something that is very rare to do and indicates an occasional failing that I hope will be put right and we will discover that this is not intended.
“Because if it is, it means we won’t in fact be stopping our contributions to the European Union, and that would be very strange.
“And to have them described as own resources is even more peculiar, because that assumes we are still members, so I think there is an error there.”
The prominent Brexiteer’s comments come as Brussels demand the UK reaches an agreement on its divorce fee before trade talks can begin.
Liz Truss, the chief secretary to the Treasury, said the OBR had been provided with Theresa May’s Florence speech on Brexit and had made their own independent forecasts.
She said: “Those forecasts are made by the OBR. The OBR were provided with the Prime Minister’s Florence speech, the basis on which we are negotiating with the EU.
“It is up to them to make their own independent forecasts.
“My understanding, and Mr Rees-Mogg will have to speak directly to the OBR about that, is they’ve used an average of other independent forecasts that have been prepared.”
Mr Rees-Mogg has been outspoken in his calls for Britain not to consider paying the EU to leave its club.
Speaking to BBC’s Sunday Politics, Mr Rees-Mogg said the EU could become “insolvent” once Britain stops its contributions.
He vowed that the UK was in the driving seat as it negotiates the so-called Brexit divorce bill with the bloc because of the Brussels’ need for funds.
Last week, the Conservative MP for North East Somerset said the ‘£350 million a week’ for the NHS pledge by Vote Leave should be honoured once Britain leaves the bloc.