Simon Coveney (Cork South Central, Fine Gael) | Oireachtas source

My understanding is the former. It is from the last time a review took place because it is about the calculation of the rent. If someone took out a tenancy four years ago and had a review two years ago, it is the calculation from the last time the rent was reviewed. That is my understanding.

With regard to Deputy Shortall's question, once a rent pressure zone is designated, it is the property that cannot see the rent increase more than 4% pro ratain a year. There cannot be another rent review within 12 months of that and when the next rent review takes place, whether it is in 12 or 18 months time, it will be on a pro ratabasis since the last review, no more than 4%-----

See this speech in context