Renewing a fixed-term lease does not automatically allow the landlord to reset the rent to any amount. For most private tenancies, rent can generally be reviewed only once every 12 months and the increase is limited by the applicable rent-control rules, usually the lower of 2% or inflation, subject to exemptions. The landlord must give at least 90 days’ notice using the required information. Check the current rules on the RTB or gov.ie, and remember that the RTB or a solicitor would assess any dispute based on the particular tenancy.