Construction Cost Index: How to Use It
The ICC is still used as a reference in certain leases and contracts. Here's how to read it as of March 30, 2026 and use it without misinterpretation.
Expert note: This article was written by our chartered accountancy firm. Information is current as of 2026. For a personalised review of your situation, contact us.
Construction cost index: how to use it
Updated March 30, 2026 - The construction cost index (ICC) remains a useful reference in certain leases, indexation clauses and real estate analyses. As of March 30, 2026, the latest available Insee publication concerns Q4 2025, with an ICC at 111.0 in base 100 in 2021 and an annual decrease mentioned by INSEE.
To complete, also see Real estate situation, Do you have to open an SCI to invest? and Family SARL or SCI.
What is the ICC still used for?
- ▸index certain old or specific contracts;
- ▸follow a price signal in construction;
- ▸compare the evolution with other real estate indices;
- ▸objectify certain reasonings of valorization or revision.
The right reflex in 2026
- ▸check the exact index provided for in the contract;
- ▸do not automatically replace ICC with ILC or ILAT;
- ▸use the correct publication date;
- ▸document the applied calculation.
Hayot Expertise Advice: an indexing file is first secured by rereading the clause. Choosing the wrong index creates more risk than the calculation itself.
You want to check an indexing clause
We can help you reread the contract, the target index and the revision method chosen.
Discover our accounting and legal support
Conclusion
As of March 30, 2026, the ICC must be used precisely: good index, good period, good clause.
Do you want to check an indexation calculation or a sensitive real estate file? We can support you.
Make an appointment with an expert
(Official sources: Insee, ICC publications as of March 24, 2026 for Q4 2025)
Article written by Samuel HAYOT
Chartered Accountant, registered with the Institute of Chartered Accountants.
Need a quote or personalised advice?
Our accountancy firm supports you through all your steps. Get a free quote to review your situation and receive a bespoke fee proposal, or contact us directly.