Rent Review Rules in Ireland: RPZ, National Rent Control & Notice Requirements

Getting a rent review right in Ireland requires attention to several overlapping rules: the minimum interval between reviews, the correct notice period, the applicable cap on increases, and the requirement to notify the RTB. A mistake at any stage can result in the increase being reversed, a refund order, or an RTB sanction. This guide explains the current rules as they stand after the March 2026 amendments.

The 12-Month Minimum Between Reviews

A landlord cannot review the rent more frequently than once every 12 months. This rule applies to all tenancies, regardless of location or property type. The 12-month clock runs from the date the current rent took effect, not from the date of the previous review notice. If you increased the rent on 1 June 2025, the earliest you can set a new rent to take effect is 1 June 2026.

The 12-month rule also applies at the start of a tenancy. If a tenant moves in on a particular rent, you cannot increase that rent until at least 12 months have elapsed since the tenancy commenced, unless the lease provides for an initial rent-free period followed by a specified increase (which is unusual in the residential market).

Where a property changes tenant, the new tenant inherits the rent review history. If the previous tenant had a rent review that took effect only 6 months ago, you must wait another 6 months before reviewing the rent for the new tenant. The clock does not reset between tenancies on the same property.

90-Day Written Notice Requirement

Before any rent increase can take effect, the landlord must serve a written rent review notice on the tenant at least 90 days in advance. This notice must include specific information:

• The amount of the new rent.
• The date from which the new rent will take effect.
• The current (existing) rent.
• A statement that the tenant has the right to refer a dispute about the new rent to the RTB within 28 days of receiving the notice.
• How the new rent was calculated, including reference to the applicable formula.
• The HICP rate or general CPI rate relied upon (where relevant).

If the notice is missing any of these elements, the tenant can challenge it at the RTB and the increase may be set aside. The 90-day period is a minimum; serving the notice earlier gives you a buffer in case of disputes about the date of receipt.

From RPZs to National Rent Control

Before March 2026, rent caps applied only within designated Rent Pressure Zones (RPZs). The RPZ cap was the lower of 2% per annum or the HICP rate of inflation. Areas outside RPZs had no cap — landlords could increase rent to market rate, subject only to the 12-month and 90-day notice rules.

The March 2026 amendments abolished the RPZ system entirely and replaced it with a national rent control regime. The same HICP-linked cap (maximum 2% per year) now applies to every residential tenancy in the State, regardless of location. The formula is straightforward: the maximum new rent equals the current rent multiplied by one plus the lower of the annual HICP rate or 2%.

For practical purposes, the key change is that landlords of properties outside former RPZs can no longer increase to market rent. If your property was in a rural area or a town that was not designated as an RPZ, you are now subject to the same cap as a Dublin city centre landlord. The cap is based on the HICP rate published by the CSO for the 12-month period ending in the quarter before the rent review takes effect.

CPI Exemption for New Construction

Newly constructed dwellings that are let for the first time after the commencement of the 2026 Act are exempt from the rent control cap for their first letting only. This means the landlord can set the initial rent at any level the market will bear. However, once the rent is set and the tenancy commences, all subsequent reviews on that tenancy are subject to the standard national cap.

This exemption is designed to protect the viability of new housing development. Without it, developers argued, the returns on new construction would not justify the cost, reducing housing supply. The exemption applies only to genuine new builds — not refurbishments, renovations, or properties that were previously let and then taken off the market.

To rely on the exemption, the landlord should retain evidence that the property is a first letting of new construction, such as the certificate of compliance with building regulations, the planning reference, and the date the property was first available for letting.

How to Calculate the Maximum Allowable Increase

The calculation involves three steps:

1. Identify the reference HICP rate. Check the CSO website for the most recently published annual HICP rate. This is typically the rate for the 12-month period ending in the most recent quarter.
2. Apply the 2% ceiling. If the HICP rate exceeds 2%, use 2%. If the HICP rate is below 2%, use the HICP rate. If the HICP rate is negative (deflation), you cannot increase the rent at all.
3. Multiply. The maximum new rent is the current rent multiplied by (1 + the applicable rate). For example, if the current rent is EUR 1,500 per month and the applicable rate is 1.8%, the maximum new rent is EUR 1,500 x 1.018 = EUR 1,527. This is typically rounded to the nearest euro.

It is critical to use the correct HICP figure. Using a general CPI figure, a different time period, or a rate from the wrong quarter will result in an incorrect calculation. The RTB has been clear that landlords bear the burden of demonstrating that their calculation is correct.

RTB Notification of Rent Changes

After serving a rent review notice on the tenant, the landlord is required to notify the RTB of the rent change. This is done through the RTB's online tenancy registration system by updating the rent details for the registered tenancy. The update should be submitted within one month of the date the new rent takes effect.

Failure to update the RTB registration is an offence and can result in a fixed penalty notice. It can also complicate matters if a dispute arises, as the RTB will refer to its registered records when adjudicating. Keeping your registration up to date is a straightforward compliance step that should not be overlooked.

What If the Tenant Disputes the Increase?

A tenant has 28 days from receiving the rent review notice to refer a dispute to the RTB. Common grounds for challenge include:

• The increase exceeds the permissible cap.
• The 12-month minimum interval was not observed.
• The notice was not served at least 90 days in advance.
• The notice was missing required information.
• The HICP rate used was incorrect or applied to the wrong period.

If the RTB finds in favour of the tenant, it can order the landlord to revert to the previous rent and refund any excess rent already collected, plus interest. In serious or repeated cases, the RTB can impose additional sanctions. The best way to avoid a dispute is to get the calculation and the notice right the first time.

Practical Tips for a Smooth Rent Review

• Start preparing your rent review at least 4 months before you want the new rent to take effect. This gives you time to check the HICP rate, calculate the increase, draft the notice, and serve it with a comfortable margin.
• Always use the CSO's official HICP data, not media reports or third-party estimates. The specific index and reference period matter.
• Keep a copy of the notice with proof of service (postal receipt, email delivery confirmation, or witness statement).
• Update the RTB registration as soon as the new rent takes effect. Set a calendar reminder if needed.
• If in doubt about the calculation, use a compliance tool to verify before serving the notice. It takes under a minute and can save months of dispute resolution.