Following high-level talks, the institute has said that the Treasury has been persuaded by its recent lobbying effort.
RIBA President Jack Pringle said that Gordon Brown's mandarins have become convinced of the need to move design up the PFI process.
Pringle had a meeting with civil servants last month about his 'smart' PFI initiative.
As a result of this meeting, the head of the Treasury's Private Finance Unit Richard Abadie said: 'The message is that authorities should do some degree of design work up front themselves, rather than leaving it to the private sector.
'This is what we will be saying in our policy message and in our presentations in future.'
Pringle said he was delighted by the statement. 'The announced change in tack by the Treasury is entirely in keeping with the recommendations the RIBA has been pursuing over a number of months.
'We are pleased we have been able to play a part in bringing design to the forefront of PFI best practice,' he added.