Checking or disputing a rent indexation as a tenant in Belgium
Last reviewed on 2026-06-10 · reading time ± 3 min
An indexation letter from your landlord is not a done deal: the calculation must follow the legal formula, and in a number of cases indexation is not allowed at all (or not in full). Here is how to check it yourself.
Step 1 — Recalculate
The legal formula is basic rent × new index ÷ starting index, using Statbel's health index. Common mistakes in indexation letters:
- the already indexed rent is indexed instead of the basic rent from the contract;
- the wrong month is used (it must be the month before the anniversary of the entry into force);
- the EPC/EPB correction factor is "forgotten" for contracts from before the 2022 freeze;
- indexation happens more than once per lease year, or more than three months retroactively.
Recalculate the exact legal maximum here — all you need is the basic rent, the contract dates and the energy label.
Step 2 — Check whether indexing is allowed at all
- Brussels: no registration of the contract or no EPB certificate presented? Then indexation is not allowed.
- Verbal contract or a contract that excludes indexation: no indexation.
- Flanders/Wallonia: for older contracts with a poor energy label, a correction factor or a continuing restriction applies.
Step 3 — Respond in writing
If the amount is wrong, reply politely but in writing, including your own calculation. In the meantime, pay the correct indexed amount (not just the old amount: you don't have to refuse a lawful indexation, only the incorrect part). Besides the landlord's letter, our letter generator also produces a verification letter for tenants with the correct figures.
If you can't work it out together
Overpaid indexation can be reclaimed up to five years back. If you can't resolve it with your landlord, you can turn to a tenants' association, free rental mediation in your municipality, or ultimately the justice of the peace — that procedure is accessible and cheap.