In a comment to be broadcast on BBC Radio 4 this evening, Andrew Wilson - who chairs the party's Growth Commission - concedes that oil revenues "was indeed a basis" for the party's financial plans during the independence referendum campaign in 2014.
This is despite Alex Salmond's repeated claim during the campaign that "oil will be a bonus."
The Scottish Conservatives are today calling on Mr Salmond to admit he got it wrong in the run up to the 2014 and deliberately misled people by trying to claim oil would not be needed to plug massive holes in an independent Scotland's finances.
Scottish Conservative shadow finance secretary Murdo Fraser said:
"The full scale of Alex Salmond's bluster and evasion in the 2014 referendum campaign is finally being exposed.
"He tried to claim oil revenues would be a "bonus" to an independent Scotland.
"As his close ally Andrew Wilson has now conceded, oil revenues were 'baked' into their numbers and formed the 'basis' for an independent Scotland's finances.
"Mr Salmond has never admitted he tried to mislead people on oil during the 2014 referendum. Now that even his own SNP colleagues are owning up, it is time he did so himself.
"If the SNP is now admitting oil is a bonus, it must set out which taxes would rise and what public services would be cut in order to fill an independent Scotland's £15bn deficit.
"Better still, the Nationalists should stop trying to make their sums work, get on with the day job, and dump their unwanted plans for a divisive second referendum."