Sinn Féin has, for the first time, provided a cost for its mortgage interest relief proposal setting it at €350-400m.
Speaking at the Oireachtas Finance Committee, Pearse Doherty said these figures had been provided by the independent Parliamentary Budget Office and the Sinn Féin plan was targeted and time-bound until the end of the year.
He said the State would absorb 30% of the increased mortgage interest charged to consumers since rates began to rise in June last year.
Mr Doherty said: "There is a massive shock for families. Many of these families are paying €5,000 more than they were last June. There is a responsibility on the State to try to cushion the shock."
He said this would amount to a maximum of €1,500 per individual.
Mr Doherty clashed with Minister for Finance Michael McGrath who said that Sinn Féin had recently called for mortgage interest relief, more welfare, an extension to redress schemes and refund payments for people in nursing homes.
Mr McGrath said: "Every week you seem to be making it up as you go along - there is a new spending proposal, a new taxation proposal, you never set out what your overall plan is.
"Beyond the Budget you keep coming forward with new items that weren't in your Budget."
The minister said Sinn Féin had a chance at the time of its alternative budget to provide relief to mortgage holders even though rates had already begun to rise, and chose not to.
Mr Doherty said the Government was now bringing forward another suite of measures outside of its budget proposals that were not included last year.
Mr Doherty said people were being fleeced and Fianna Fáil and Fine Gael had allowed mortgages to be sold to vulture funds.
Mr McGrath said: "If you ever get into Government, there will be great fun in replaying all the social media clips and videos of everything you said in opposition because you won't be able to deliver them.
"You're not a fool and you know that in your heart of hearts."
