Dublin no longer has a separate rent cap: from 1 March 2026, national rent-control rules apply instead of the former Rent Pressure Zone system. For most existing private tenancies, rent can generally be increased only once every 12 months by the lower of 2% or the change in the Consumer Price Index (CPI). The landlord must give the required written notice, normally at least 90 days, and follow the statutory calculation rules. Limited exceptions may apply, so check the RTB’s rent calculator and current guidance; the outcome of any dispute depends on the tenancy’s facts.