The Taoiseach has refused to comment on speculation that a property tax may be introduced in December's Budget.
Fine Gael Leader Enda Kenny described media reports of a possible property tax as grossly unfair.
Mr Kenny said he would oppose any such plan.
He said less than one in ten of the proposed cuts in the McCarthy plan had been implemented and until the plan was executed it was unfair to ask families to take more pain.
Brian Cowen said he could not speculate on what would be in the Budget.
Mr Cowen acknowledged that the Programme for Government contained a proposal for a site tax and said the commission of taxation had recommended widening the tax base.
