A landlord cannot increase the rent simply because a probationary period is ending. Irish law does not generally create a separate statutory type of “probationary tenancy”, so any increase must comply with the rent rules applying to the tenancy, including timing, limits and notice requirements. These rules can depend on when the tenancy began, the property’s location and whether newer national rent-control provisions apply. Check the latest guidance on gov.ie or the RTB website, and consider getting advice from a qualified housing adviser or solicitor if the proposed increase appears unlawful.