Galway was covered by Rent Pressure Zone rules, which generally limited rent reviews to once every 12 months and the lower of 2% or inflation (HICP). From 1 March 2026, national rent-control rules apply instead, with the same broad cap for existing tenancies, subject to limited legal exceptions. A landlord must give the required written notice and explain the calculation; a rent increase cannot normally take effect without proper notice. If you believe the increase is unlawful, the RTB can decide a dispute based on the tenancy’s facts, and you can check the current rules on gov.ie or seek legal advice.