ILAT indexation: calculate the new rent of your lease
The ILAT (French tertiary activities rent index) is used to index the annual rent of offices, warehouses and premises of liberal professions. Here are the latest values published by INSEE, the calculation formula with a worked example and a free calculator, no sign-up.
Official ILAT values
Quarterly index published by INSEE (base 100 in Q1 2010). The one-year change compares the index with the same quarter of the previous year: this is the change applied by an annual indexation.
| Quarter | ILAT index | One-year change | Published in the Journal officiel |
|---|---|---|---|
| Q2 2026 | 138.01 | +0.63% | 25 Sep 2026 |
| Q1 2026 | 137.42 | +0.09% | 28 Jun 2026 |
| Q4 2025 | 137.21 | -0.06% | 26 Mar 2026 |
| Q3 2025 | 137.07 | -0.04% | 17 Dec 2025 |
| Q2 2025 | 137.15 | +0.51% | 24 Sep 2025 |
| Q1 2025 | 137.29 | +1.60% | 2 Jul 2025 |
| Q4 2024 | 137.29 | +2.69% | 26 Mar 2025 |
| Q3 2024 | 137.12 | +3.76% | 18 Dec 2024 |
| Q2 2024 | 136.45 | +4.45% | 25 Sep 2024 |
| Q1 2024 | 135.13 | +5.09% | 29 Jun 2024 |
The ILAT indexation formula
New rent = current rent × (ILAT revision index ÷ ILAT reference index).
The reference index is the one set by the lease's indexation clause, usually the index of the signing quarter or the one used at the previous indexation. The revision index is the index of the same quarter one year later.
Worked example with official indices
An office is let for €2,000 excl. VAT per month, indexed annually on the Q2 ILAT. Reference index: Q2 2025 = 137.15. Revision index: Q2 2026 = 138.01 (Journal officiel of 25 September 2026).
New rent = 2,000 × 138.01 ÷ 137.15 = €2,012.54 per month, a 0.63% increase. With a Q4 clause the rent goes down: Q4 2025 (137.21) is below Q4 2024 (137.29), so €2,000 becomes €1,998.83.
Frequently asked questions
What is the latest ILAT value?
As of 26 October 2026, the latest published ILAT is Q2 2026: 138.01 (Journal officiel of 25 September 2026), up 0.63% year on year from Q2 2025 (137.15).
Which leases use the ILAT?
Leases of premises used for tertiary activities other than retail or crafts: offices, warehouses and logistics platforms, premises of liberal professions. Shops and craftsmen use the ILC.
Can ILAT indexation lower the rent?
Yes. At the end of 2025 the ILAT fell year on year (-0.04% in Q3, -0.06% in Q4). A clause allowing only increases is deemed unwritten under French case law.
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