Rent increases are strictly regulated
Outside of annual indexation (health index), the rent can only be increased by mutual written agreement or by a decision of the justice of the peace at the end of each three-year period. The landlord cannot unilaterally raise the rent. Any increase must be proportional and justified by changed circumstances or property improvements.
Belgian residential lease law protects tenants against arbitrary rent increases. The rent agreed at the start of the lease is the “base rent” that can only evolve through the legally prescribed mechanisms. This stability is a cornerstone of tenant protection in Belgium.
The annual indexation based on the health index is the only routine adjustment. It compensates for inflation and applies automatically (though the landlord must claim it). Any increase beyond indexation requires either the tenant’s agreement or a court order.
Methods to increase the rent
| Method | When | Conditions | Formality |
|---|---|---|---|
| Annual indexation | Each lease anniversary | Health index formula | Written request |
| Mutual agreement | Any time | Both parties consent | Written addendum |
| Court revision | End of 3-year period | Changed circumstances | Justice of the peace |
| New lease | At lease renewal | New negotiation | New contract |
Mutual agreement is the simplest method. The landlord and tenant agree on a new rent and sign an addendum to the lease. This addendum must be registered with the FPS Finance. The tenant is never obliged to accept an increase.
A new lease after the 9-year term expires allows the landlord to propose a new rent based on current market conditions. The tenant can negotiate or refuse and leave.
If you are a landlord seeking a rent increase beyond indexation, the best approach is to make property improvements and then request a revision at the end of the three-year period. Document all improvements with invoices and before/after evidence.
Rent revision by the justice of the peace
At the end of each three-year period, either party can request a rent revision from the justice of the peace:
- Timing — the request must be filed between 9 and 6 months before the end of the current three-year period
- Grounds for increase — the landlord must prove that new circumstances have increased the normal rental value by at least 20% (e.g. significant neighbourhood improvements)
- Grounds for increase after works — if the landlord has carried out works at their own expense that increase the rental value by at least 10%
- Grounds for decrease — the tenant can also request a decrease if circumstances have reduced the rental value by at least 20%
The justice of the peace will assess whether the requested increase is justified by comparing the current rent with the normal rental value for similar properties in the area. The judge has full discretion to set the new rent.
Regional specifics
Brussels-Capital Region
The ordinance of 27 July 2017 regulates rent revisions in Brussels. The indicative rent grid (grille indicative des loyers) published by the Brussels Region can serve as a reference for the justice of the peace when assessing whether a rent revision is justified.
Walloon Region
The decree of 15 March 2018 follows similar principles for rent revision. Wallonia does not have a mandatory rent grid but market comparisons are used by judges to assess revision requests.
Flemish Region
The Vlaams Woninghuurdecreet of 9 November 2018 provides comparable rent revision mechanisms. Flanders uses objective valuation criteria, including the property’s energy performance, to assess revision requests.
Regional housing legislation (Brussels ordinance 2017, Walloon decree 2018, Flemish decree 2018) on rent revision at the end of each three-year period. The revision mechanism is uniform in principle across regions.