Chapter 2 of 10 · Rent · 6 of 8
The 2% or CPI cap: this month's figure
How the cap is worked out, which CPI figure applies to your review date, and the RTB calculator as the official check.
Checked 27 OCT 2026 · 4 sourcesWritten in plain English for the person paying the rent. This guide covers the Republic of Ireland only.
This month the cap is 2%. The Consumer Price Index for September 2026 rose 4.1% on the year. The CSO published it on 8 October 2026, and because it is above 2% the ceiling is the lower of the two arms. A rent review notice served now cannot raise the rent by more than 2%, and never above market rent.
The cap is the lower of 2% and the annual change in the CPI. When inflation runs above 2% the cap is 2%. When it runs below, as it does now, the CPI figure is the cap. The rent increase checker applies the right month's figure to your rent, and the RTB's rent calculator is the official check.
How the cap is worked out
Since 1 March 2026 section 19 of the Residential Tenancies Act, as amended, caps a rent increase anywhere in the State at the lower of two figures. The first is 2%. The second is the annual percentage change in the Consumer Price Index, the all-items index the Central Statistics Office publishes each month.
The percentage is applied once, to the current rent. A landlord who has not reviewed the rent for several years does not get several years of increases. The cap is a single figure for a single review, however long the gap. The arithmetic is the current rent multiplied by the percentage, added to the current rent.
| Current rent | Cap this month | Most the increase can be | Most the new rent can be |
|---|---|---|---|
| €1,000 | 2% | €20.00 | €1,020.00 |
| €1,500 | 2% | €30.00 | €1,530.00 |
| €1,839 | 2% | €36.78 | €1,875.78 |
| €2,200 | 2% | €44.00 | €2,244.00 |
Those figures are the cap, not an entitlement. The new rent must also be no more than market rent for a similar home, shown by three comparable tenancies from the RTB's Rent Register begun within the last three months. Where market rent is below the capped figure, market rent wins.
Which CPI figure applies to your notice
The CSO publishes the CPI each month, for the month before. Each release gives the annual change, and that is the figure the cap uses. The September 2026 release of 8 October 2026 gave 4.1%, above the ceiling, so 2% applies from 8 October 2026 until a release brings the CPI below 2%.
The RTB's calculator picks the figure that applies to the dates you enter, and its result is the official one. The landlord must attach its printout to the review notice, so the figure the landlord used is on the page in front of you. Run the same dates yourself. Our checker uses the same CSO series and names the month it used, so you can see whether the two agree.
A new CPI release can move the cap between the day a notice is served and the day the new rent starts. The notice is judged on the figure the calculator gives for its dates, not on a figure that arrives later.
When the cap is 2% and when it is the CPI
| Annual CPI change | The cap |
|---|---|
| 4.1% (September 2026) | 2% |
| 2.0% | 2% |
| 3.5% | 2% |
| 0.5% | 0.5% |
| Below zero | No increase on the formula |
Inflation ran well above 2% through 2022 and 2023, and in those years the cap was 2% everywhere it applied. The CPI arm bites only in a month when inflation is below 2%; at 4.1% it is the 2% ceiling again. The figures page carries the CPI series alongside the RTB's rent figures, so you can see where the cap has been.
Who the cap applies to
Every tenancy under the Residential Tenancies Act, in every county, whenever it began. There are no zones, and there is no difference between a tenancy that began in 2015 and one that began last month in the figure the landlord may apply. Rent increase rules from 1 March 2026 is the full rule.
The exceptions are few. A newly built apartment, or new student-specific accommodation, with a commencement notice lodged on or after 10 June 2025 may rise with CPI alone, with no 2% ceiling. This month that is 4.1% against 2%, so the rule matters. A home not let for two years, or one year for a protected structure, may be let at market rent. A tenancy that began on or after 1 March 2026 may be reset to market at the end of a six-year cycle. The CPI-only rule and when rent can be reset to market cover those.
If you rent a room in the owner's own home you are a licensee, and the cap does not apply to you.
Checking a notice against the cap
Five questions decide whether a review notice is within the law.
| Question | What the Act requires |
|---|---|
| When was the rent last set? | At least 12 months before the new rent starts (24 under the transitional rule for late RPZ areas) |
| What percentage is applied? | No more than the lower of 2% and the CPI figure for the dates |
| Is the new rent above market? | It cannot be; three comparables from the Rent Register show market |
| How much notice? | At least 90 days, in the prescribed form, with the calculator printout and the comparables |
| Did the RTB get a copy? | Within 7 days of service (the same day from 1 March to 13 September 2026) |
The rent increase checker runs the first three for you and dates the other two. The rent review notice takes the form and the attachments item by item.
If the figure is over the cap, keep paying the current rent and refer a dispute to the RTB at least 28 days before the new rent would start. The review is paused while the dispute runs. The RTB can order rent paid over the cap repaid, with damages of up to €20,000. Since 14 September 2026 it can also serve the landlord with a fixed payment notice of €200 for a rent breach. Challenging a rent increase sets out the steps, and Threshold on 1800 454 454 will read the notice with you.
Where this leaves you
The cap is the lower of 2% and the CPI's annual change, applied once to the current rent, never above market. This month that is 2%, because the September 2026 index published on 8 October 2026 rose 4.1%. The RTB's calculator is the official figure, and the landlord must attach its printout to the notice. Run your own rent and dates through the checker, compare the two printouts, keep paying the current rent, and refer a dispute in time if they do not match.
Questions people ask
What is the rent increase cap in Ireland this month?
2%. The Consumer Price Index for September 2026 rose 4.1% on the year, published on 8 October 2026, and that is above the 2% ceiling, so the ceiling is the lower arm. A rent review notice served from 8 October 2026 cannot raise the rent by more than 2%, and never above market rent. The RTB's rent calculator is the official figure.
Is the cap 2% or the rate of inflation?
Whichever is lower. When inflation runs above 2% the cap is 2%. When inflation runs below 2%, as it does this month, the CPI figure is the cap. The index is the CSO's Consumer Price Index, all items, annual change.
Can the landlord add up the years he did not increase the rent?
No. The cap is applied once, to the current rent, at each review. A landlord who left the rent alone for three years gets one capped increase, not three. There is no catching up.
Where do I find the official figure?
On the RTB's rent calculator at rtb.ie. Enter the current rent, the date it was last set and the date of the review, and it gives the most the new rent can be. The landlord must attach its printout to the review notice. Our checker uses the same rule and the same CSO series.