Cork has been covered by rent-control measures, although the rules have changed and the correct position depends on when your tenancy began and whether it is an existing or new tenancy. In general, a landlord must follow the applicable limit, cannot usually increase the rent more than once in 12 months, and must give formal written notice with the required information and notice period. Check the current rules and RTB guidance for your specific tenancy, as exceptions can apply. If you believe an increase is invalid, you can seek advice from Threshold or ask the RTB about dispute resolution.