For most private tenancies in Dublin, rent can generally be reviewed only once every 12 months and the increase is limited to the lower of inflation (CPI) or 2%. The landlord must give the required written notice, explain how the new rent was calculated and provide the effective date; 90 days’ notice is generally required. Different rules and exemptions can apply, particularly to newer tenancies or where a tenancy has ended, so check the RTB’s current guidance and rent calculator. Any dispute about whether an increase is valid is ultimately decided through the RTB process or by a solicitor.