Abusive clauses are null and void by operation of law
An abusive clause in a lease is automatically null and void under Book VI of the Belgian Code of Economic Law. The tenant can have the clause annulled by the justice of the peace without invalidating the rest of the lease. The judge can even raise the issue of abusive clauses on their own initiative.
Belgian law provides strong protection against abusive clauses in contracts, including leases. A clause is considered abusive when it creates a significant imbalance between the rights and obligations of the parties, to the detriment of the consumer (in this case, the tenant).
The nullity of an abusive clause is absolute: it cannot be validated by the tenant’s consent or by the fact that the tenant signed the lease knowingly.
How to challenge an abusive clause
If you identify an abusive clause in your lease:
- Notify the landlord in writing (registered letter) explaining why you consider the clause abusive
- Request removal or modification of the clause by mutual agreement
- If the landlord refuses, file a claim before the justice of the peace (juge de paix)
- The judge will assess whether the clause creates a manifest imbalance
- If abusive, the clause is annulled; the rest of the lease remains in force
The tenant does not need to prove actual harm — it is sufficient to demonstrate that the clause creates an imbalance in principle.
BailBelgique generates leases that comply with all regional legislation, automatically excluding prohibited clauses.
Common abusive clauses
The following types of clauses are typically considered abusive in Belgian residential leases:
| Clause type | Why it is abusive |
|---|---|
| Waiver of tenant’s mandatory rights | Cannot waive rights protected by mandatory law |
| Notice period exceeding 3 months | Law caps tenant’s notice at 3 months |
| Disproportionate penalty clause | Must be reasonable and proportionate to actual damage |
| Automatic rent increase beyond indexation | Only legal indexation is permitted |
| Prohibition of all pets | A blanket ban may be considered disproportionate |
| Obligation to use landlord’s contractor | Restricts tenant’s freedom of choice |
| Waiver of the right to go to court | Fundamental right that cannot be waived |
The assessment is always case-by-case. A clause that is acceptable in a commercial lease may be abusive in a residential lease, and vice versa.
Regional specifics
Brussels-Capital Region
The Brussels ordinance of 27 July 2017 includes a list of mandatory provisions that cannot be derogated from to the tenant’s detriment. Any clause that contradicts these provisions is automatically null.
Walloon Region
The Walloon decree of 15 March 2018 contains similar mandatory provisions. Wallonia also requires specific information annexes, and failure to provide them may render related clauses unenforceable.
Flemish Region
The Flemish Housing Rental Decree of 9 November 2018 provides a comprehensive framework with mandatory provisions. Flanders has been particularly active in codifying which clauses are permitted and which are not.
Belgian Code of Economic Law, Book VI (unfair contract terms) + Regional housing legislation — Abusive clauses are null and void by operation of law.