Four new local electoral areas have been designated as Rent Pressure Zones from today.
Rents in Baltinglass in West Wicklow, Piltown in Kilkenny, Sligo-Strandhill and Cobh in Cork will only be able to go up by four percent a year.
It brings to 25 the number of areas brought under RPZ rules this year.
Meanwhile, the latest figures from the Residential Tenancies Board shows national rents increased by 8.2 percent this year.