Rent increase calculator
Rent increase calculator: how much can the rent go up?
The national limit from 1 March 2026: inflation since the rent was last set, or 2% a year pro rata, whichever is lower. Plus every deadline around the notice.
The rule in one paragraph
Take the rent as last set and the date it was set. Count the full months to the date of the new notice. The permitted increase is the smaller of the CPI change over those months and 2% a year pro rata. The new rent must also not be above market rent for similar homes, which is why the notice cites three comparable tenancies from the Rent Register. Notice is 90 days on the prescribed form, once in 12 months, with a copy to the RTB within 7 days.
Questions
Is the 2% cap a flat 2%?
No, it is 2% a year pro rata to the months since the rent was last set: 24 months allow 4%, 6 months allow 1%. Inflation is measured over the same months. The lower of the two applies.
Which inflation figure is used?
The Consumer Price Index, all items, published monthly by the CSO. We use the index for the month the rent was last set and the month of the new notice. If the latest month is not published yet, the most recent one is used, exactly as the RTB calculator does.
Does the whole country count as a Rent Pressure Zone now?
From 1 March 2026 the same rules apply everywhere in the State. Where a tenancy began before its area was designated a Rent Pressure Zone, 24 months must pass between the last rent setting and the next review; after that the 12-month rule applies.
What about new apartments?
Homes in new or extended apartment developments where building started on or after 10 June 2025 follow inflation only, with no 2% cap. The 90-day notice, the form and the comparables still apply.
Is this the official calculator?
No. The RTB publishes its own calculator and the notice form asks for its printout. Ours uses the same index and the same arithmetic, to the cent, and adds the deadlines and the tenant view. Run both; they agree.