On 16 April 2026, INSEE published the rent reference index (IRL — Indice de Référence des Loyers — the French rent reference index) for the first quarter: 146.60, a rise of 0.78% year-on-year. For a rent of €850 a month, that means an authorised increase of barely €6.63 — provided you ask for it correctly. Many landlords forget to do so, lose the benefit of the past year, or apply an increase they are not entitled to claim.
Revising a rent in 2026 is anything but automatic. The increase is capped by an official index, it requires a clause in the lease, it cannot be backdated indefinitely, and it is simply forbidden for dwellings rated F or G under the DPE (Diagnostic de Performance Énergétique — the French Energy Performance Certificate). This article sets out how to calculate the increase to the last cent and which mistakes cost you money — or expose you to a refund.
Q1 2026 IRL: 146.60 (+0.78% year-on-year) — published in the Official Journal on 16 April 2026 by INSEE. This is the rate at which revised rents indexed on this quarter may rise.
What this article covers
You will find here the exact definition of the IRL, the legal framework for annual rent revision (Act of 6 July 1989), the formula for calculating the increase with a detailed worked example, the rules on backdating and on notifying the tenant, and the cases where revision is frozen — in particular thermal sieves (passoires thermiques — energy-inefficient dwellings) rated F and G. All of it up to date with the 2026 indices.
The legal framework for rent revision with the IRL
The annual revision of the rent on a dwelling let unfurnished as a main residence is governed by article 17-1 of Act no. 89-462 of 6 July 1989 aimed at improving landlord-tenant relations. This revision is only possible if the lease contains an express revision clause. Without such a clause, the rent stays frozen for the entire term of the contract: the landlord cannot increase it, even if the index rises.
The rent reference index (IRL) is the official index published each quarter by INSEE (the French National Institute of Statistics and Economic Studies). It serves as the legal ceiling for revision: the increase applied can never exceed the variation in the IRL between two dates. The IRL corresponds to the average, over the last twelve months, of the consumer price index excluding tobacco and excluding rents. It was defined in its current form by Act no. 2008-111 of 8 February 2008.
| Item | Content | Legal basis |
|---|---|---|
| Mandatory revision clause | No clause in the lease = no revision possible | Act of 6 July 1989, art. 17-1 |
| Ceiling index | Quarterly IRL published by INSEE | Act of 8 February 2008 |
| Backdating of the request | Limited to one year from the request | Act of 6 July 1989, art. 17-1 |
| Freeze on F and G rents | Revision forbidden for thermal sieves | Climate & Resilience Act of 22 August 2021 |
Two recent developments have reshuffled the deck. First, the "rent shield" introduced by the Act of 16 August 2022 (the emergency purchasing-power protection act) temporarily capped the variation in the IRL at +3.5% in mainland France: this measure expired at the end of 2024, so the IRL now applies without any cap. Second, the Climate & Resilience Act of 22 August 2021 (law no. 2021-1104) introduced, with effect from 24 August 2022, a freeze on the revision and indexation of rents for dwellings whose energy consumption exceeds the threshold of classes F and G of the DPE. The landlord of a thermal sieve can therefore no longer increase the rent — neither during the lease, nor at renewal, nor between two tenants.
How to calculate the rent increase with the IRL in 2026
The revision calculation rests on a single formula, simple as long as you identify the right indices. The principle: you apply to the current rent the ratio between the IRL of the reference quarter set in the lease and the IRL of that same quarter a year earlier.
The official revision formula
New rent = current rent × (IRL of the reference quarter ÷ IRL of the same quarter the previous year). The "reference quarter" is the one stated in the lease; failing any mention, it is the most recent index published on the date the contract was signed. The golden rule: you always compare the same quarter from one year to the next (a Q1 with a Q1, a Q3 with a Q3), never two different quarters.
The Q1 2026 IRL is 146.60 and rises by 0.78% year-on-year: for a lease whose reference quarter is Q1, the maximum increase applicable in 2026 is therefore 0.78%. This is a moderate pace, well below the 2022-2023 peaks, reflecting the easing of inflation that the index measures. For comparison, the Q1 2025 IRL was still rising by 1.40% year-on-year, and the Q1 2023 index had jumped by 3.49%: the slowdown is clear.
Identifying the right reference quarter
The reference quarter is the pivot of the calculation, and it is also the leading source of error. In principle it is stated in the lease: each contract indicates which quarter (Q1, Q2, Q3 or Q4) the IRL used as the basis for the revision is keyed to. Failing any express mention, case law takes the most recent IRL index published on the date the lease was signed. Once that quarter is set, it no longer changes for the entire term of the contract: you revise each year using the same quarter, simply moving the two compared indices forward by one year.
In practice, you need two values: the IRL of the reference quarter for the year of the revision, and the IRL of the same quarter the previous year. Both indices are published by INSEE and reproduced by ANIL (the French National Housing Information Agency) in a quarter-by-quarter summary table. Carry them over without rounding before calculating the coefficient: it is the final rounding, on the rent, that is done to the cent.
When and how the revision takes effect
The revision date is generally the anniversary date of the lease, unless the contract sets another date. This is what is known as the "anniversary date" effect. The landlord must request the application of the revision: it does not trigger by itself. The request can be made by letter, by email or via the rent statement. As long as it is not made, the rent stays at the previous level.
Profile: private landlord letting an unfurnished apartment as a main residence, lease signed in 2024, revision clause indexed on the Q1 IRL, dwelling rated D or better (therefore eligible for revision).
Backdating is limited to one year
If the landlord forgets to revise on the anniversary date, all is not lost: article 17-1 of the Act of 6 July 1989 allows the revision to be caught up, but backdating is capped at one year from the request. In practice, a landlord who has not revised for three years can only claim the catch-up for the last twelve months: the increases of the earlier years are definitively lost. The revision therefore does not accumulate indefinitely: it becomes time-barred, which is an incentive to formalise the request every year.
| Situation in the lease | Revision possible? | Practical effect |
|---|---|---|
| Revision clause + dwelling rated A to E | Yes, capped at the IRL | Maximum increase = variation in the IRL of the reference quarter |
| No revision clause | No | Rent frozen for the entire term of the lease |
| Dwelling rated F or G | No (freeze since 24/08/2022) | No indexation or revision as long as the property stays F or G |
Case study: revising an €850 rent in 2026
Let's take a realistic illustrative example. You let an unfurnished 42 m² apartment in Lyon, whose monthly rent excluding charges stands at €850 — an order of magnitude consistent with the rent levels observed for a one-bedroom flat in the Lyon metropolitan area. The lease, signed in March 2024, contains a revision clause indexed on the Q1 IRL. The dwelling is rated D, so it is eligible for revision.
Scenario — Revision on the March 2026 anniversary date
| Item | Calculation detail | Amount |
|---|---|---|
| Current rent | Monthly rent excluding charges before revision | €850.00 |
| Q1 2026 IRL | Index published by INSEE in the Official Journal of 16/04/2026 | 146.60 |
| Q1 2025 IRL | Index of the same quarter the previous year | 145.47 |
| Revision coefficient | 146.60 ÷ 145.47 | 1.007768 |
| New rent | 850.00 × 1.007768 | €856.60 |
| Monthly increase | 856.60 − 850.00 | €6.60 |
The authorised increase comes to about €6.60 a month, or nearly €79 over the year. This is the direct application of the 0.78% rise in the IRL. Note: the value 145.47 used here for the Q1 2025 IRL is consistent with a 0.78% annual progression of the index; for a real calculation, always use the two exact indices as published by INSEE for your reference quarter. The result must be rounded reasonably (to the cent), and the revised rent applies from the date of your request, with no possibility of going back more than one year.
The mistakes that cost you the revision (or the money)
Mistake no. 1 — Believing the revision is automatic
The revision does not trigger by itself on the anniversary date. You must request it from your tenant. If you wait, you lose the benefit of the increase beyond one year of backdating. Many landlords discover, after several years without revising, that they can only catch up the last year.
Mistake no. 2 — Comparing two different quarters
The formula requires comparing the same quarter from one year to the next. Using the Q1 2026 IRL against the Q3 2025 one distorts the calculation and exposes you to an illegal increase, and therefore to a refund if the tenant challenges it. Always check the reference quarter stated in your lease.
Mistake no. 3 — Revising the rent of a thermal sieve
For a dwelling rated F or G, the revision and indexation of the rent have been frozen since 24 August 2022 under the Climate & Resilience Act. Applying an increase to a thermal sieve has no legal basis: the tenant is entitled to demand a refund. The only way to regain the right to revise is to renovate the property so that it leaves classes F and G.
⚠️ Warning: the rent shield that capped the IRL at +3.5% expired at the end of 2024. The index now applies in full: do not carry over an old +3.5% cap into your 2026 calculations — it no longer exists.
Mistake no. 4 — Forgetting the revision clause when signing
Without a revision clause in the lease, the rent is frozen for the entire term of the contract. This omission, common on leases drafted in haste, deprives the landlord of any indexation until renewal. Always check that this clause is present and correctly worded before signing.
Calculate your 2026 rent revision in seconds
Mon Simulateur Immobilier IRL rent revision calculator
Enter your current rent, the reference quarter of your lease and the IRL indices concerned: the calculator applies the official formula (rent × reference IRL ÷ previous-year IRL), works out the revision coefficient and displays the new rent together with the authorised monthly and annual increase.
To go further: also check the maximum rent calculator for rent-controlled areas and measure the impact on yield with the rental yield simulator.
Conclusion
Rent revision in 2026 follows a precise mechanism: a clause in the lease, an IRL ceiling index (146.60 in Q1 2026, i.e. +0.78% year-on-year), an explicit request to the tenant and backdating limited to one year. The slightest slip — the wrong quarter, an increase applied to an F or G thermal sieve, an outdated +3.5% cap — turns a legitimate increase into a challengeable one.
To secure the calculation and avoid any mistake, the Mon Simulateur Immobilier IRL rent revision calculator applies the official formula to your figures and tells you the exact revised rent as well as the authorised increase, to the last cent.
