An 80-year-old landlord taxed EUR 12,000 per year for not having re-let his house after his tenant's death. A landlord whose property was devastated by fire, taxed EUR 20,000 because the works are taking too long. A 91-year-old man penalised EUR 1,500 for a dilapidated cornice. These concrete cases, widely reported in the specialist press and by landlord associations, illustrate a growing drift: "behavioural" taxes that punish situations rather than income. What property managers need to know — and how to respond.
What is a behavioural tax on property?
Behavioural taxes are municipal or regional levies that do not tax income or a transaction, but a behaviour judged abnormal by the public authorities: a vacant property, a deteriorated facade, a property not registered in the planning register.
The distinction from a fine is fundamental. A fine penalises an infringement — it is proportionate to the seriousness of the failing, governed by procedural rules, and subject to specific appeal routes. A property tax is in principle linked to ownership of a property, not to behaviour. When a tax is in reality a disguised sanction, it steps outside the constitutional framework of taxation and into the domain of criminal law — with the procedural guarantees that implies.
Professional federations and landlord associations have been warning for several years about the proliferation of these taxes in Belgian municipalities, particularly in Brussels and Wallonia. By 2026, the situation has worsened further.
The most common types of behavioural tax
The vacancy tax: up to EUR 24,000 per year
The vacancy tax applies to housing considered uninhabited or unlet. It exists in Wallonia, Brussels, and many Flemish municipalities.
The amounts can be very high:
- In Wallonia: variable by municipality, potentially reaching several thousand euros per year
- In Brussels: up to EUR 24,000 per year per unit, under the Brussels Housing Code
The central problem is the definition of vacancy. A property vacant due to works, an ongoing inheritance process, or a succession dispute can be considered "vacant" even where the landlord has legitimate reasons for not occupying or letting it. The Brussels Housing Code provides exemptions, but their application by municipal administrations is often strict and sometimes arbitrary.
The tax for properties not listed in the planning register
Certain Brussels municipalities, including Berchem-Sainte-Agathe, have introduced a tax of EUR 4,000 per year for each unit not listed in the planning register. For landlords whose properties have undergone undeclared modifications in past decades, this tax can apply without their having been previously informed.
The tax for a deteriorated facade
Several Brussels municipalities levy taxes on facades considered to be in poor condition. The definition of what constitutes "poor condition" is often left to the assessment of the municipal officer, without clearly established objective criteria.
Three concrete cases that illustrate the drift
Mr A., 80, in Ixelles: EUR 12,000 for not re-letting
Mr A. is 80 years old. He has lived in his house since birth. His tenant died. He decided, at his age, not to re-let the upper floor — an entirely understandable and legal decision.
The municipality of Ixelles applied the vacancy tax: EUR 12,000 per year for the vacant upper floor. Despite a police report confirming that Mr A. does occupy the rest of the house, the tax was maintained. The matter is currently before the Brussels regional mediator.
This case illustrates the absurdity of certain applications: an elderly owner-occupier who chooses not to re-let part of their own home finds themselves penalised as if they were engaged in speculative retention of property.
Mrs J., in Brussels: EUR 20,000 after a fire
Mrs J.'s property was devastated by a fire. Reconstruction works are under way, but they are taking time — insurance expert assessments, permit applications, and construction phases all take their course.
The City of Brussels concluded that the works were taking too long and applied a one-off tax of EUR 20,000 for the vacant property. No consideration was given to the objective constraints (insurance, permits, construction works) explaining the delay. The matter is before the courts.
This case raises a fundamental question: how can an administration tax a landlord who is the victim of a disaster for not having rebuilt quickly enough?
Mr C., 91, in Saint-Gilles: EUR 1,500 for a cornice
Mr C. is 91 years old. His facade has a cornice in poor condition, but the facade itself is not dilapidated. The municipality of Saint-Gilles applied a tax of EUR 1,500 for a deteriorated facade — based on a criterion that Mr C. contests.
At 91, undertaking cornice restoration works requires steps (permits, a tradesperson, financing) that cannot be resolved in a few weeks. The tax penalises a situation without taking into account the personal circumstances and the complexity of the steps involved.
Why some of these taxes are legally contestable
The Council of State precedent against Schaerbeek
The Council of State has already annulled a similar municipal tax in a landmark ruling: C.E. no. 219,721 of 12 June 2012 (challenge to the municipality of Schaerbeek). The grounds for annulment: the competence to introduce this type of tax on vacant housing was reserved to the Brussels Region, not to municipalities. A municipality that exceeds its fiscal competences sees its tax annulled.
This precedent is important: it shows that municipal property tax litigation is contestable legal terrain.
The principle of non-retroactivity and legal certainty
Behavioural taxes are often introduced without sufficient prior notice to affected landlords. Where a landlord has not been informed of the application criteria and exemption possibilities, the tax can be challenged on the basis of the principle of legal certainty.
The proportionality of sanctions
Belgian administrative law requires that sanctions be proportionate to the failings identified. A tax of EUR 24,000 per year for a vacant unit may be considered disproportionate depending on the circumstances — particularly where the landlord has legitimate reasons for not letting (inheritance, works, dispute).
How to respond to a behavioural tax: a four-step procedure
Step 1: Request an in-person meeting with the administration
On receipt of a tax notification or formal notice, immediately request a face-to-face meeting with the responsible officer or official. A direct discussion often allows the situation to be clarified, the criteria applied to be understood, and possibilities for exemption or amicable regularisation to be explored.
Step 2: Send a registered letter with acknowledgement of receipt
Alongside the meeting, send a registered letter setting out the reasons for the alleged failing. This letter should:
- Describe the actual situation of the property and the reasons for its condition or vacancy
- Mention the steps under way or planned
- Explicitly request the application criteria for the tax and the possibilities of exemption
- Be sent within the challenge deadlines provided by the municipal regulations (often 30 days)
The registered letter creates an opposing record: it proves that you acted promptly and in good faith.
Step 3: Challenge before the competent authorities
If the amicable route fails, several appeal bodies are available depending on the situation:
- The delegated official: for regional taxes, the administrative appeal goes through the competent delegated official
- The ombudsman or regional mediator: to obtain independent mediation with the administration
- The courts: to challenge the legality or proportionality of the tax before the competent administrative or civil courts
- The Council of State: for questions of regulatory legality (as in the Schaerbeek precedent)
Step 4: Engage a specialist lawyer
Challenging a municipal or regional tax is a complex procedure requiring precise knowledge of local fiscal and administrative law. A lawyer specialising in municipal and regional taxation is essential for significant cases (tax exceeding EUR 5,000 or administrative appeal).
Specialist municipal-tax lawyers and professional bodies can help you find appropriate support for this type of litigation.
What property managers should put in place preventively
Rigorous documentary monitoring by property
The best defence against a behavioural tax is an irreproachable documentary file. For each property:
- Photograph the condition of the property regularly (year by year)
- Retain leases, notice letters, and lease expiry notices
- Archive planning permits, works quotes, and contractor invoices
- Record all exchanges with administrations (registered letters, emails, meeting minutes)
Report unusual situations promptly
When a property remains vacant for more than a few months, managers should notify the administration promptly — explaining the reasons (inheritance, works, dispute) and documenting the steps under way. This proactive approach reduces the risk of a tax and constitutes an element of defence in the event of proceedings.
Know the local exemption regimes
Vacancy taxes generally include exemptions for properties under renovation, properties subject to court proceedings, properties in inheritance, and so on. These exemptions vary from one municipality to another. Managers must know the regimes applicable in the municipalities where they manage properties.
With Seido, every exchange with the administration is tracked and timestamped: formal notices, responses, photographs of the property's condition. In the event of a challenge to a behavioural tax, you have a complete and structured file — a powerful argument before the ombudsman or the courts. Document your exchanges →
This article is part of Property Essentials #3 — March 2026. Also read: Mortgage interest deduction removed — Winter moratorium: two rulings confirm the right is not absolute.
Sources and references
- Analysis by Olivier de Clippele, Le Cri no. 502, March 2026, pp. 24–26
- Council of State, ruling no. 219,721 of 12 June 2012 — annulment of a municipal tax (Schaerbeek)
- Landlords' alarm call in Brussels, La Libre, 03/01/2026
- Brussels Housing Code — provisions on vacant housing