For a tenancy covered by Rent Pressure Zone rules, check the permitted increase using the RTB’s current rent calculator and give the required notice, normally at least 90 days. A simple template is: “Dear [tenant], following a rent review, the rent will change from €[old amount] to €[new amount] per month from [date]. This is an increase of [percentage], calculated under the applicable RPZ rules; the next payment is due on [date]. Yours sincerely, [landlord].” The notice should include the calculation and be served on the tenant and RTB as required. The RTB or a solicitor can confirm whether the calculation and notice are valid for your tenancy.