What conditions for rent indexation?
Rent indexation in Belgium is governed by precise rules:
1. A written lease. Indexation is only possible if the lease is in writing. An oral lease does not allow indexation.
2. The anniversary date. Indexation takes effect at the earliest on the anniversary of the lease coming into force, i.e. the day the tenant took possession of the property.
3. A written request from the landlord. Indexation is never automatic. The landlord must notify the tenant in writing (letter, email). Without a request, the rent remains unchanged.
4. No exclusion clause. If the lease contains a clause excluding indexation, the landlord cannot apply it.
Indexation can only be applied retroactively for the 3 months preceding the request. If the landlord forgets to index for 2 years, they can only claim 3 months of arrears.
How to calculate rent indexation?
The legal formula is as follows:
Indexed rent = base rent x new index / starting index
- Base rent: the rent agreed at the start of the lease (or the last rent fixed by the court or by agreement between the parties).
- New index: the health index of the month preceding the anniversary of the lease coming into force.
- Starting index: the health index of the month preceding the signing of the lease.
The health indices are published monthly by the FPS Economy (Statbel). The result is rounded to two decimal places.
Regional exceptions and limits
Brussels-Capital Region: For housing with a poor EPC certificate (E, F or G), indexation may be limited or prohibited. This measure aims to encourage energy renovation.
Walloon Region: Indexation follows federal rules without additional EPC-related restrictions for the time being.
Flemish Region: The Vlaams Woninghuurdecreet also provides for indexation limitations for energy-inefficient housing (EPC E or F): indexation limited to 50% for EPC E, and prohibited for EPC F.
Use the BailBelgique indexation calculator to get the exact amount in a few clicks, with up-to-date indices.