The Oireachtas housing committee will today formally call for a vacant property tax to be introduced.
They'll recommend the measure in a new report that'll be published this afternoon.
It's aimed at bringing tens of thousands of homes back into use, to be available to rent or buy.
Sinn Féin's housing spokesman, Eoin Ó Broin, is on the committee - he's backing the proposed tax.
"There should be a cost if somebody, for no good reason, is sitting on a vacant property in the middle of a housing crisis.
"We can't punish people on Fair Deal, or whose properties are on probate.
"But anyone speculatively sitting on a vacant property should pay a cost, and that should be in my view a tax on the market value of the property, incrementally increasing each year, to push that property into use."
