Since 1 March 2026, an Irish rent increase is capped nationally at the lower of 2% or inflation — the same cap everywhere, now that Rent Pressure Zones have ended. A tenancy can be reviewed at most once every 12 months, and a Notice of Rent Review must be served at least 90 days before the new rent starts, with a copy sent to the RTB the same day. Get the figure or the notice wrong and the increase is invalid and disputable. TenantSync's National Rent Cap calculator returns the maximum legal rent in about 30 seconds and generates a compliant notice — from your phone. There's a free calculator and a free 14-day trial, no card required.
A rent review is one of the few moments in a tenancy where a small mistake has an outsized cost. Set the increase a few euro too high, or serve the notice a few days short, and the entire increase can be struck down at the RTB — and any excess you've collected repaid. The maths itself is simple. The danger is doing it against the wrong reference figure, or missing a timing rule that changed in 2026.
The good news: this is exactly the kind of rule-based calculation a phone does perfectly. Once you understand what the cap is and what a valid notice requires, the actual work takes seconds. This guide covers both — the rules, and the fastest way to get them right every time.
This is a guide, not legal advice
Rent rules and the relevant inflation figure change and are fact-specific. This article explains the general position for private residential tenancies since 1 March 2026. Confirm the current cap, inflation measure and notice requirements for your own tenancy with the RTB before serving a rent increase.
What changed when Rent Pressure Zones ended
For years, whether — and by how much — you could raise the rent depended on where the property was. Inside a Rent Pressure Zone (RPZ), increases were tightly capped; outside one, different rules applied. Landlords and agents spent real time checking whether a given address was in a designated zone.
Since 1 March 2026, that geography is gone. A single national rent cap applies, so the question is no longer "is this property in an RPZ?" but simply "is this tenancy due a review, and what's the capped figure?" That's simpler in principle — but it also means the old habits and old reference points no longer apply, and anyone still calculating the way they did before the change risks getting it wrong.
The cap got simpler and more universal at the same time. One rule, everywhere — which is easy to state, and easy to apply with the right tool.
The cap: the lower of 2% or inflation
The national cap limits a rent increase to the lower of two numbers:
- 2% — a fixed ceiling, and
- inflation — the relevant official inflation figure for the period.
You apply whichever is lower. If inflation is running above 2%, the 2% ceiling governs. If inflation is below 2%, that lower figure is your maximum. The "2%" is a ceiling, not an entitlement — you don't automatically get 2% just because a year has passed; you get up to the lower of the two figures, and only if the tenancy is actually due a review.
"Whichever is lower" is where people slip
The common error is to assume the answer is always 2%. It isn't. When inflation is below 2%, applying a flat 2% overshoots the cap and makes the whole increase invalid. The safe move is to check both figures every time — which is exactly what a calculator does for you, so you never rely on a stale assumption.
Get the maximum legal rent in about 30 seconds
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A worked example: 2% vs inflation
Say a tenant has been in place over a year, the rent is €1,500, and the tenancy is due a review. The cap is the lower of 2% or inflation, so it depends which figure is smaller:
| Scenario | Governing figure | Maximum new rent |
|---|---|---|
| Inflation is above 2% (say 3%) | The 2% ceiling | €1,500 × 1.02 = €1,530 |
| Inflation is below 2% (say 1.5%) | Inflation, 1.5% | €1,500 × 1.015 = €1,522.50 |
The difference between the two is small in euro, but the consequence isn't: charge €1,530 in the second scenario and you've breached the cap by €7.50 a month, which is enough to make the entire increase invalid if it's disputed. That's the trap of doing it in your head — the arithmetic is easy, but the reference figure is the part that catches people. A calculator that always checks both numbers removes the risk entirely.
The notice & timing rules that make it stick
Calculating the right figure is only half the job. The increase is only valid if it's served correctly, and 2026 added a rule that catches people out:
- Once every 12 months. Rent can be reviewed at most once a year. A review served too soon after the last one is invalid, whatever the figure.
- At least 90 days' notice. A Notice of Rent Review must be served on the tenant at least 90 days before the new rent takes effect.
- Same-day RTB copy. Since 1 March 2026, a copy of the notice must be sent to the RTB on the same day it's given to the tenant — miss this and the review is invalid.
- Show your working. The notice must state the new rent and how it was calculated under the cap.
The same-day RTB copy is the new trap
Plenty of landlords serve a perfectly valid figure with proper notice, then forget to send the RTB its copy on the same day — and the whole review falls. It's a small step with a big consequence, and exactly the kind of thing a notice generator should handle for you so it can't be forgotten.
The calculator in your pocket
This is where an app changes the job entirely. Instead of looking up the current inflation figure, checking whether it's above or below 2%, doing the multiplication and then assembling a compliant notice by hand, you let the app do all of it:
1. The maximum legal rent, in seconds
Open the National Rent Cap calculator, and for a given tenancy it returns the maximum legal rent under the current cap in about 30 seconds — always applying the lower of 2% or inflation, so you never rely on a stale assumption or the wrong figure.
2. A compliant Notice of Rent Review, generated for you
Once you have the figure, TenantSync helps you produce a compliant Notice of Rent Review (the Section 12 notice) — with the correct 90-day lead time and the same-day RTB copy the rules now require — so the increase actually stands rather than falling on a technicality.
3. Tied to the tenancy, not a loose spreadsheet
Because the calculator lives against the tenancy record, TenantSync also knows the last review date and won't let you review too soon — and it tracks the RTB registration and renewal deadlines on the same tenancy. The rent review stops being a standalone task and becomes part of a tenancy that's watched for you. It's the same compliance engine behind staying fully RTB-compliant for €20 a month.
Try the free National Rent Cap calculator
Use the free calculator to get the maximum legal increase for a tenancy — then start a free 14-day trial to generate the Notice of Rent Review and track every review date automatically.
Why a phone-friendly calculator actually matters
A rent review rarely happens at a desk. You're at a viewing when a prospective tenant asks what the rent will be next year; you're on the phone to a tenant discussing a renewal; you're standing in the property deciding whether an increase is worth it. In those moments, "I'll check when I'm back at the computer" is how a review gets delayed or done carelessly.
Having the calculator in your pocket means you can answer accurately on the spot — quote a figure you know is legal, and start the notice while you're thinking about it. For an agent, it's a credibility signal in front of a landlord client; for a self-managing landlord, it's the difference between a review that happens on time and one that slips another few months. The whole point of building TenantSync for iOS and Android, not just the web, is that lettings decisions happen away from the desk.
Common mistakes that make an increase invalid
Almost every invalid rent increase comes down to one of a short list of errors — all avoidable:
- Assuming the cap is always 2%. When inflation is lower, 2% overshoots and invalidates the increase.
- Reviewing too soon. More than one review inside 12 months is invalid, however small.
- Short notice. Fewer than 90 days before the new rent starts.
- Forgetting the RTB copy. Not sending the RTB its copy on the same day the tenant is served.
- No working shown. A notice that doesn't state the new rent and how it was calculated.
Every one of these is a process error, not a judgment call — which means a tool that follows the process can prevent all of them. That's the case for calculating in an app instead of in your head.
How to get started
- Try the free calculator to see the maximum legal rent for a tenancy.
- Start your free 14-day trial — no credit card required.
- Download the app on iOS or Android, or use the web platform.
- Add your tenancy — the calculator ties to it, and the RTB and review dates are tracked for you.
- Generate the Notice of Rent Review with the correct timing and the same-day RTB copy built in.
Frequently asked questions
How much can I increase rent in Ireland in 2026?
Since 1 March 2026 a rent increase is capped nationally at the lower of 2% or inflation. If inflation is above 2%, the 2% ceiling applies; if it's below 2%, the lower inflation figure is the maximum. This replaced the Rent Pressure Zone system, so the cap now applies regardless of location. Confirm the current inflation figure and the rules for your tenancy at rtb.ie.
How do I calculate a legal rent increase in Ireland?
Take the current rent, apply the lower of 2% or the relevant inflation figure, and that's the maximum new rent — but only if the tenancy is due a review (once every 12 months) and you serve a valid Notice of Rent Review. Doing it by hand risks the wrong reference figure. TenantSync's National Rent Cap calculator returns the maximum legal rent in about 30 seconds and helps you generate a compliant notice, from your phone or the web.
Is there a free rent increase calculator for Ireland?
Yes. TenantSync has a free National Rent Cap calculator you can use before signing up — enter the current rent and it returns the maximum legal increase. Inside an account, the calculator ties to each tenancy and works with a Notice of Rent Review generator and RTB deadline tracking, so the whole review is handled in one place. There's a free 14-day trial, no card required.
How often can I review the rent on a tenancy?
At most once every 12 months. Even a fully compliant increase can only be applied once a year, and a review served too soon is invalid. TenantSync tracks each tenancy's last review date so you know when the next one becomes due and a date can't quietly slip. Confirm the current rules at rtb.ie.
What notice do I have to give for a rent increase in Ireland?
A Notice of Rent Review must be served on the tenant at least 90 days before the new rent takes effect, and since 1 March 2026 a copy must be sent to the RTB on the same day the tenant is served — otherwise the review is invalid. The notice must also state the new rent and how it was calculated. TenantSync generates a compliant notice with the correct timing and same-day RTB copy built in.
What happens if I set the rent increase too high?
An increase above the cap is invalid. The tenant can dispute it at the RTB, the increase won't stand, and you can be required to repay any excess collected. That's why calculating against the correct figure and serving a valid notice matters. TenantSync's calculator returns the maximum legal rent so you never overshoot, and the notice generator keeps the paperwork defensible.