A French landlord cannot freely raise the rent of an existing tenant. The 1989 Act allows exactly three situations in which a mid-tenancy rent increase is lawful: the annual IRL index revision, an increase following improvement works, and — rarely — a realignment of a manifestly under-priced rent at renewal. Outside these cases, any increase is null. Here's how each mechanism works, what blocks it (DPE F/G, zone tendue), and the mistakes that cost landlords money.
Case 1 — Annual IRL index revision
The standard mechanism. Prerequisite: the lease must contain a revision clause. Without one the rent is frozen until the next renewal.
Formula: new rent = current rent × (IRLN / IRLN−1), where both indices are for the same quarter one year apart. The IRL is published quarterly by INSEE.
Timing: once a year on the lease anniversary date (or the date specified in the contract). If the landlord does not request the revision within 12 months of the anniversary date, the revision is permanently lost for that year — it cannot be deferred or accumulated.
Worked example
Current rent: €800 — IRL Q2 2025: 146.63 — IRL Q2 2024: 143.46
New rent = 800 × (146.63 / 143.46) = €817.66 (+2.21%)
Case 2 — Improvement works increase
Outside zone tendue: if the landlord carries out improvement works at their own expense (insulation, heating upgrade, full renovation) and the cost reaches at least 50% of one year's rent, a mid-tenancy increase is allowed, capped at 15% of the actual TTC cost per year. It must be agreed in a signed addendum before the works begin.
In zone tendue areas: improvement works do not entitle the landlord to a mid-tenancy increase — only to a capped uplift at re-letting. See our rent control zone tendue guide.
Case 3 — Manifestly under-priced rent (at renewal only)
Strictly speaking this applies at renewal, not mid-tenancy. If the rent is manifestly below comparable market rents in the neighbourhood, the landlord may propose a realignment when the lease comes up for renewal. The procedure is heavily regulated (three market-rent references required, proposal must be sent at least 6 months before expiry) and, if disputed, the departmental conciliation commission rules. It is rarely pursued without legal advice.
Never miss a revision with automation
A missed revision costs a landlord €150–300 per property per year on average. Property management software recalculates the IRL on each anniversary date, generates the revision notice, and updates the rent in force — with no manual intervention. Use the FacturZen IRL calculator to simulate the new rent before applying it.
Never miss another rent revision — FacturZen calculates and applies the IRL automatically on each lease anniversary date.
Frequently asked questions
Must the landlord notify the tenant before applying an IRL revision?
The law sets no formal notification requirement for IRL revisions, but best practice is to send a written notice (letter or email) with a detailed calculation at least one month before the anniversary date. This avoids disputes and gives the tenant time to adjust. Most property management software applies the revision automatically on the anniversary date.
What happens if the landlord misses the annual revision date?
The missed revision is lost for that year — it cannot be carried over or added to the following year's revision. If the landlord requests it late (e.g. 8 months after the anniversary date), the revision applies only from the date of the request, using the IRL in force at that time. Backdating is not allowed.
Can the tenant refuse the IRL revision?
No — not if the lease contains a valid revision clause. The IRL revision is a contractual right. The tenant can however challenge it if the calculation is wrong (wrong quarter, wrong reference IRL) or if the property is rated DPE F or G, in which case no revision is allowed at all.
Does the IRL revision also apply to service charges?
No. The annual IRL revision applies only to the base rent (loyer nu), not to service charge provisions. Provisions are reconciled separately each year against actual expenditure. See our guide on rental charges reconciliation.
How do I calculate the applicable IRL for my lease anniversary?
The formula is: new rent = current rent × (IRL for reference quarter N / IRL for same quarter N-1). The reference quarter is usually the one before the lease anniversary, as specified in the contract. IRL figures are published quarterly by INSEE and are available on the FacturZen IRL calculator.
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