Can a rent indexation be refused in Belgium?
Tenant or landlord, when is a refusal of indexation legitimate? List of valid and invalid grounds under Belgian law.
Brief answer
In Belgium, a tenant can refuse a rent indexation only in legally precise cases: unregistered lease, calculation error, or retroactivity exceeding 3 months. Subjective grounds (rent “already high”, absence of prior notice, financial situation) are not valid. Conversely, a landlord can waive indexation for a given year without losing their right for subsequent years.
Practical rule: before any escalation, verify the calculation. Our calculator automatically applies the official Statbel formula and indicates the exact base index and new index.
Refusing: a framed right, not a free opposition
The indexation of residential rents is governed by article 1728bis of the Belgian Civil Code and the Law of 6 August 1993 on lease contracts. These texts state a simple principle: if the lease is registered and the landlord makes a written request, indexation is by right.
The word “refuse” is therefore misleading. For the tenant, it is not about accepting or declining a contract, but verifying that the request is legally founded. If they have a valid ground, the refusal stands before the justice of the peace. Otherwise, they expose themselves to a conviction and costs.
On the landlord’s side, the verb “refuse” has a different meaning: it is the possibility to waive for a given year, with no consequence on subsequent years. Our guide on tenant refusal covers in more detail the landlord’s recourses when the tenant wrongly contests.
The 3 VALID refusal grounds for the tenant
1. Unregistered lease
Registration of the lease at the competent registration office is mandatory within 2 months following the signature, at the landlord’s charge. Without registration, the right to indexation does not exist, regardless of elapsed time. The tenant can refuse without compensation, and the landlord has no recourse as long as the lease is not regularised.
This is the most radical effect of non-registration. See our guide on unregistered leases for the procedure of regularisation a posteriori and its tax consequences.
2. Calculation error
The official formula is:
Indexed rent = Initial rent × (Health index of the month preceding the anniversary ÷ Health index of the month preceding the signature)
Any deviation from this formula (wrong month, wrong indexes, omission of the EPC coefficient applicable in Brussels or Flanders) makes the indexation request partially or fully contestable. The tenant can refuse the calculation and demand a new corrected notification.
3. Retroactivity exceeding 3 months
Article 1728bis, §1 of the Civil Code limits the retroactive effect of the indexation request to the 3 months preceding the month of the request. If the landlord claims 3 or 5 years of arrears at once, the tenant can refuse the excess part and pay only the last 3 months indexed.
The NON-valid refusal grounds (the most common)
| Ground invoked | Legal status | Consequence if refusal persists |
|---|---|---|
| « The rent is already too expensive » | Invalid | Possible conviction + costs |
| « You did not warn me in advance » | Invalid (no legal notice) | Idem |
| « My income has dropped » | Invalid (personal ground) | Idem |
| « The EPC of the dwelling is poor » | Partially valid in Bxl/Flanders, otherwise invalid | Coefficient to apply correctly |
| « You forgot for several years, it’s your fault » | Invalid for the part within 3 months | Payment of the last 3 months |
| « I prefer to negotiate » | Legally invalid | Landlord keeps their right |
A tenant who relies on one of these grounds takes a real risk: if the landlord refers the matter to the justice of the peace (quasi-free procedure), they will be ordered to pay the arrears and, generally, the costs.
How to refuse correctly?
If the tenant believes they have a valid ground among the three above, the recommended procedure is as follows:
- Reply in writing to the landlord, ideally by registered mail with acknowledgment of receipt, within 15 days of the indexation notification
- State the exact ground for the refusal (for example: « Unregistered lease, indexation not enforceable » or « Calculation error: incorrect base index used »)
- Continue paying the non-indexed rent to avoid being in payment default elsewhere
- Keep all evidence (copy of the lease, registration certificate or its absence, corrected calculation)
If the landlord persists despite a valid ground, it is they who will have to refer the matter to the justice of the peace — and they will be dismissed.
For an illegitimate refusal (rent too expensive, etc.), the tenant has every interest in not formalising their refusal and paying: engaging in a standoff with an invalid ground will only generate costs.
Special case: the landlord who « refuses » to index
On the landlord’s side, refusing to index means waiving for a given year. This is legally possible and without negative consequences:
- No obligation to index each year — the right is exercised or not, at the landlord’s convenience
- The waiver for one year does not apply for subsequent ones (no contractual precedent)
- The landlord can recover at most the last 3 months by sending a late request (art. 1728bis, §1)
This flexibility is useful for commercially managing the relationship with a good tenant or for absorbing an exceptional inflationary shock without passing on the entire increase.
And the justice of the peace in all this?
If the disagreement persists, the competent court is the justice of the peace of the commune where the dwelling is located. The procedure is:
- Free (fiscal stamp of about 50 €)
- Without mandatory lawyer — anyone can present themselves alone
- Fast: hearing in 4 to 8 weeks on average
- Decided by a single judge specialised in rental disputes
The judge first checks the registration of the lease, then the calculation of the indexation, then respect for the retroactivity limit of 3 months (art. 1728bis, §1). If everything is compliant, the tenant is ordered to pay the arrears and generally the costs.
To go further
- Calculate the indexation correctly — verify before accepting or refusing
- The tenant refuses: landlord’s recourses — the procedure on the landlord’s side in detail
- Unregistered lease and indexation — the no. 1 valid refusal ground
- Standard notification letter — ready-to-send PDF template
- Methodology — legal sources used by our calculator
Indexation is a right, not a negotiation. But this right is exercised within a strict formal framework: it is this framework that founds a legitimate refusal, and only it.
Frequently asked questions
Can the tenant refuse the indexation because the rent already seems too high? + −
No. Subjective feeling about the rent level does not constitute a legal ground for refusal. The only criterion that matters is the formal compliance of the request with article 1728bis of the Civil Code. If the request is regular (registered lease, correct calculation, exact Statbel indexes), the tenant cannot oppose it. For this type of disagreement, an amicable renegotiation of the rent is the appropriate path, not a refusal of indexation.
If the landlord did not give me prior notice, do I have the right to refuse? + −
No. Belgian law imposes no prior notice before the anniversary date. The indexation takes effect from the receipt of the written request. The absence of prior notice is not a valid ground for refusal. The landlord can perfectly notify on the anniversary date itself, or even after — the request then having retroactive effect only for the 3 months preceding the month of the request (article 1728bis, §1 of the Civil Code), but without loss of the right itself.
Can a retroactive indexation be refused? + −
Yes, partially: the indexation request has retroactive effect only for the 3 months preceding the month of the request (article 1728bis, §1 of the Civil Code). If the landlord claims more than 3 months of indexation arrears, the tenant can refuse the excess part. The part within the last 3 months remains, however, due and enforceable.
The lease is verbal: can I refuse the indexation? + −
For a residential lease as primary residence, a verbal lease has been legally presumed valid since 2007 but mandatory registration is impossible without a written document. Case law mostly considers that an unregistered lease does not give rise to indexation. In practice, negotiate the writing and registration of the lease before any discussion on indexation.
If I refuse the indexation, can the landlord terminate my lease? + −
Not directly for this single ground. But if the landlord refers the matter to the justice of the peace and obtains a favourable judgment, you will be ordered to pay the arrears. Failing payment, the characterised payment default may justify a request for resolution of the lease in a subsequent procedure. Refusing a valid indexation thus exposes you to costs and, in time, a risk to the maintenance in the premises.
Does the landlord also have the right to 'refuse' (waive) indexation? + −
Yes. Indexation is a right of the landlord, not an obligation. They can perfectly choose not to index a given year — as a commercial gesture, to retain a good tenant, or by oversight. This tacit waiver does not create a precedent: the landlord can request indexation again the following year, and recover at most the 3 months preceding the month of their request (art. 1728bis, §1 of the Civil Code).
Calculate your indexation
Our tool automatically applies the Belgian legal formula with up-to-date Statbel indexes.
Go to the calculator →This article is informational and does not constitute legal advice. For any disputed or complex situation, consult a lawyer or the justice of the peace of the property's commune (free procedure).