Property taxes should be higher for homes that are not occupied, according to one financial analyst.
Karl Deeter was speaking as a new analysis of Census data from HomeHak finds that over 389,000 households in Ireland have at least two spare bedrooms.
It also notes that on Census night, there were just short of 788,000 households with at least one spare bedroom - equating to at least 1.2 million unoccupied bedrooms around the country.
This has prompted new calls for homeowners to rent out a room.
Mr Deeter told The Pat Kenny Show the answer here is tax.
"We basically under-tax housing in a big way - in other countries, property taxes are far higher," he said.
"We should probably lower labour taxes and raise things like property taxes.
"You could even look at, say, making... a property database, and you could link PPS numbers to houses.
"You could determine how many people are living there so that you could say, 'Look, the tax actually goes up if your house isn't occupied'.
"That in some way then helps to change that behaviour.
"Irish behaviour is hold on forever, never sell, give it to your kids one day."
'Sufficient supply'
Mr Deeter said in order to allow people to downsize, the supply has to improve.
"The solution there is to have a sufficient supply of houses, that if you sell a big house, you can buy a small one and have money left over," he said
"In that, you actually help alleviate poverty in an elderly population, [and] it helps free up houses.
"The issue really boils back to the same thing: we're very good about the carrot style of influence in this country.
"We're not too good at the stick," he added.
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