By How Much Can a Landlord Raise the Rent in Belgium?

For tenants and landlords alike, the question of by how much rent can be raised is particularly pressing right now. Energy prices, price indices and new energy-performance rules are causing a great deal of confusion. The key point to understand is that a landlord cannot simply increase the rent whenever they feel like it. In the vast majority of cases, rent can only be indexed according to a fixed statutory formula, and at most once a year. A genuine "increase" above and beyond that indexation is only possible in exceptional, strictly regulated circumstances - and almost always requires the intervention of a judge.

In this guide we explain what is and is not allowed: when indexation is permitted, how to calculate the maximum increase, what role the energy performance certificate (EPC) label plays, and what you can do if an increase seems unjustified.

1. Basic rule: the rent is fixed for the duration of the lease

At the start of the tenancy, the tenant and landlord agree on a base rent. This is the bare rent, excluding charges and expenses.

Key principles:

• That rent is fixed for the entire duration of the contract.
• During the lease, the landlord may not freely increase the rent.
• The only automatic "increase" provided for is indexation according to the health index - and even then, only if the relevant conditions are met.

If the landlord wants to go further than indexation - for example because they have carried out renovations or feel that the rent is "too low" - this falls under a formal rent revision procedure.

2. Rent indexation: when and by how much can the landlord raise the rent?

The most common way in which rent increases is through annual indexation. This is what most people mean when they talk about "raising the rent".

When is indexation allowed?

• At most once a year.
• No earlier than the anniversary of the date the lease came into effect (not necessarily the date of signing).
• Only if indexation is not excluded in the contract.
• The landlord must request indexation in writing; it does not happen automatically.
• If the landlord requests indexation late, they may go back a maximum of 3 months.

In other words: your landlord cannot raise the rent mid-year "because everything is more expensive" - they must wait until the contract anniversary and follow the statutory formula.

By how much can the rent increase? (formula)

The law provides one mandatory formula:

Indexed rent = base rent × (new index / starting index)

Where:

• Base rent = the rent stated in the original contract, excluding charges and expenses.
• Starting index = the health index for the month preceding the entry into force of the original contract (in Flanders, since 2019, this is the month before the entry into force; elsewhere it is generally the month before the date of signing).
• New index = the health index for the month preceding the anniversary of the date the lease came into effect.

This ensures that the landlord cannot increase the rent "at their own discretion". The rise follows the evolution of the cost of living, as measured by the health index.

You can check the calculation yourself using the official rent calculator provided by Statbel: enter the base rent, the starting index and the new index to obtain the maximum permitted rent.

3. EPC label and correction factors: an additional restriction on indexation

Since the energy crisis, the Belgian regions have introduced additional rules that limit indexation for energy-inefficient properties. The broad picture:

• For properties with a favourable EPC label (A, B, C), the landlord can in principle apply full indexation according to the formula.
• For properties with weaker labels (D, E, F) or no EPC certificate, indexation may be subject to correction factors or (temporary) restrictions, depending on the region and the period in question.
• In practice, this means the actual increase to your rent may be lower than the "theoretical" indexation figure - or may temporarily have been prohibited altogether.

Because these rules change over time and vary by region, it is important to check:

• what EPC label your property holds;
• when your contract came into effect;
• what indexation rules applied at that time in your region.

If in doubt, consult your region's official website - for example wallonie.be, logement.brussels or vlaanderen.be - for the most up-to-date corrections and exceptions.

4. Rent revision: increases above indexation

If the landlord wants to raise the rent by more than the index - for example after major renovation works - this is no longer indexation but a formal rent revision.

Important points:

• This is only possible in limited circumstances, for example when the rental value has risen significantly.
• It must often be initiated within a specific time frame (for example around the third anniversary of the contract).
• The intervention of a justice of the peace is usually required if tenant and landlord cannot reach an agreement.
• The landlord therefore cannot unilaterally decide to charge an extra €100 on top of the index "because the market rate is now higher".

Separate, specific rules apply to student or commercial leases, but the principle remains the same: a genuine increase above indexation requires a legal basis and, in most cases, judicial scrutiny.

5. By how much can your landlord actually raise your rent?

To summarise:

• During a running lease, the landlord may raise your rent only once a year, via indexation on the contract anniversary date.
• The maximum increase follows the official indexation formula and any applicable EPC corrections.
• Beyond that index, they may not unilaterally raise the rent, except through a revision procedure subject to strict conditions.
• The increase can never be backdated, except for a maximum of 3 months in the case of late indexation.

In practical terms, this means:

• If you receive a letter or email announcing an increase:
  • check whether it is an indexation applied on the correct date;
  • verify the amount using the Statbel rent calculator;
  • check whether the EPC label and any applicable restrictions have been taken into account.
• If the increase appears significantly higher than the index, or occurs mid-year without a clear basis, there is a good chance that your landlord is overstepping the legal limits.

6. What can you do if an increase seems unjustified?

As a tenant, you do not have to simply accept an unjustified increase. Steps to take:

1. Check the calculation
   • Use the rent calculator (Statbel) and the official index figures.
   • Review your contract: is indexation included or excluded?
2. Ask the landlord for an explanation
   • Politely explain why you believe the amount is incorrect.
   • Include your own calculation.
3. Does the dispute continue?
   • Contact a tenants' union or legal advice service in your region.
   • As a last resort, you can take the matter to the justice of the peace to have the increase reviewed.

If you are a landlord yourself and want to index correctly, always use the official formula and tools. This will help you avoid disputes and ensure you stay within the legal limits.