Analysis that helped the Housing Minister Simon Coveney design the Help-to-Buy scheme has not been released, despite calls from Fianna Fáil.
The Department of Housing had told the Irish Independent that it would make a study of the market, which was carried out during the summer, available - but it was not provided at the time of going to print.
Fianna Fáil has now claimed that it doesn't believe a proper market impact analysis of the scheme was compiled prior to the Budget.
Earlier this week Education Minister Richard Bruton told the Dáil: "Of course, an independent analysis has been done by the Department responsible for developing these programmes."
However, it has emerged that the analysis referred to by Mr Bruton was actually carried out internally in the Department of Housing.
Fianna Fáil's housing spokesman Barry Cowen said he believes Mr Bruton was being "disingenuous".
"I don't believe they have one. What they are terming as a market impact analysis is really just a review of the current market," he said.
"Every dog on the street knows that prices are only going to go up on the back of this scheme."
Fianna Fáil wants a cost-benefit analysis of thresholds which will allow first-time buyers spending €600,000 on a property claim €20,000 in a tax rebate.
Mr Coveney has defended the initiative, saying it is linked directly to the value of the house a person is buying.
He said the thresholds were set so as to avoid a "cliff effect" whereby somebody who spends €400,000 will get a grant and somebody who spends €405,000 won't.
"We don't expect that first-time buyers are going to be buying houses above €400,000 in any numbers at all.
"The focus here is about helping first-time buyers who are locked out of the market," he said.