Since May 1, 2025, the legal framework governing residential leases in the Brussels-Capital Region has undergone yet another significant evolution.
By activating key provisions of an Ordinance (regional law) adopted in 2021, the Brussels legislator has introduced a formal prohibition for landlords to offer a rent deemed “excessive.”
This measure, aimed at regulating the private rental market in a context of housing pressure and crisis, alters the balance of contractual freedom that had previously prevailed in rent determination.
For many landlords and investors—who make up 86% of the Brussels rental market—this regulation is perceived as a frontal attack, a “paradigm shift” that calls into question the very foundations of the landlord–tenant relationship.
This article aims to unpack the mechanics of this new prohibition and provide you with strategic insights to navigate this profoundly reshaped rental landscape.
What Is an “Excessive Rent”?
Article 224/1 of the Brussels Housing Code now provides that “The landlord is required not to propose an excessive rent.” This simple phrase marks a break from the previous regime, under which rent amounts were, in principle, freely determined by the parties.
To define what constitutes an excessive rent, Article 224 establishes a double presumption mechanism. A rent is thus presumed excessive in two distinct cases:
- Quantitative criterion: when the rent “exceeds its reference rent by twenty percent.” This mathematical 20% threshold introduces an apparently objective standard in assessing whether a rent is excessive.
- Qualitative criterion: when the rent, even if it does not exceed the 20% threshold, applies to a dwelling that “has substantial quality defects inherent to the dwelling or its environment.” This second criterion ensures that even a seemingly moderate rent can be challenged if the property’s quality is clearly insufficient.
This entire mechanism rests on a new cornerstone: the reference rent.
The Reference Rent: How It Works
Calculable through an official online tool (http://loyers.brussels), the reference rent must now be mandatorily stated in all new residential lease agreements, in accordance with Article 218 of the Code.
The use of the term “presumed excessive” is no accident—it completely reverses the burden of proof. If the agreed rent exceeds the 20% threshold above the reference rent, it is automatically deemed excessive unless the landlord proves otherwise. To justify this deviation, the landlord must demonstrate the presence of “substantial comfort features,” effectively requiring them to build a solid justification file even before any dispute arises.
This obligation to prepare a detailed file also applies when the rent does not exceed the reference rent by 20%. Indeed, a rent may still be deemed excessive if the tenant claims the property “has substantial quality defects.” This new framework forces landlords to adopt a proactive and meticulous approach to documentation (photos, plans, invoices, etc.).
The Reference Grid: The Central Point
The reference rent—and the grid that underlies it—is the engine of the entire system. It is also the source of intense controversy between landlords’ associations and tenants’ unions.
On one side, the National Union of Property Owners and Co-Owners has voiced strong objections, arguing that the grid produces “artificially low” reference rents, potentially rendering more than half of Brussels’ rental contracts excessive. The union criticizes perceived geographic inconsistencies and claims that the valuation of comfort features (garage, second bathroom, energy renovations) is disconnected from actual costs and insufficiently incentivizing. A constitutional appeal has been filed before the Constitutional Court on these grounds.
On the other hand, tenants’ unions defend the measure as a necessary social advance, emphasizing the deep wealth imbalance between landlords and tenants. In the face of a documented housing crisis (31% of the population living in overcrowded conditions), tenants see the grid as an essential first safeguard.
However, this extreme polarization around the reference grid may have perverse consequences. The perception of unfairness—whether justified or not—shapes investment decisions. A landlord might hesitate to undertake costly energy renovations if rental returns are capped at a level deemed insufficient. Others may choose to sell their properties or withdraw from the Brussels market altogether, creating an “investor exodus.” In the medium and long term, such a dynamic could exacerbate the very housing crisis the law intended to solve.
In Case of Dispute: A Two-Track Procedure
When a disagreement arises, the new legislation offers a two-tiered procedure for asserting rights.
As a first step, either party (tenant or landlord) may refer the matter to the Joint Rental Commission. This body—composed in principle of representatives of both landlords and tenants—issues a non-binding opinion on the fairness of the rent.
The Commission’s role is primarily informational, aiming to foster conciliation. Its referral is optional before initiating legal proceedings. However, its opinion can serve as useful evidence to support either party’s position before the Justice of the Peace. It can therefore function as a low-cost strategic tool, a kind of “trial run” to gauge the other party’s arguments.
When a binding decision is required, the Justice of the Peace remains the only effective authority empowered to order a rent adjustment. The law specifies precise deadlines for filing such actions: starting from the third month for short-term leases, and from the fourth month for nine-year leases.
Before the judge, the debate will revolve around the evidence provided by each party. The landlord must demonstrate that the property’s comfort features justify the rent charged, while the tenant will emphasize any quality deficiencies.
Conclusion: Navigating a Transforming Rental Landscape
The Brussels ordinance on excessive rents is far more than a mere price control mechanism. It fundamentally restructures the legal relationship between landlords and tenants by establishing a new presumption-based logic that places landlords on the defensive.
The Brussels rental market is thus entering an era of legal and economic uncertainty, where contractual freedom is now framed by a reference grid that is both central and contentious.
The real impact of this legislation remains to be seen. It will depend on how Justices of the Peace interpret “substantial comfort features,” on how the Joint Rental Commission functions in practice, and above all, on the outcome of pending appeals before the Constitutional Court. The risk of declining investment and deterioration of the rental market is real and should not be underestimated.
In this polarized legal environment—where every lease can become a potential dispute and the value of your assets depends on a contested grid—improvisation is no longer an option. Anticipate, document, and defend are now the guiding principles of property management in Brussels.
With its deep expertise in rental and real estate law, Vanbelle Law Boutique positions itself as your strategic partner to audit your rental investments, secure your contracts, and defend your interests with precision and conviction.
