When can you index the rent?

The rent can be indexed on the lease anniversary date

The right to index the rent is governed by Article 1728bis of the Belgian Civil Code. Key rules:

• Frequency: once per year only — no more frequent indexation is permitted
• Trigger date: the anniversary of the lease’s entry into force
• Written request: the landlord must notify the tenant in writing
• No advance indexation: the request cannot be made before the anniversary date
• Distinction: the entry into force may differ from the signing date

How to identify the correct indexation date

The date of entry into force of the lease is stated in the lease agreement. It corresponds to the date from which the tenant is entitled to occupy the property and the rent is due.

Example: a lease signed on 15 February 2023 with entry into force on 1 March 2023. The indexation date is 1 March each year, not 15 February.

To identify the correct date:

1. Check the lease for the “entry into force” or “start date” clause
2. If not explicitly stated, it is generally the date from which rent is payable
3. The first indexation can be requested on the first anniversary of this date

What if you miss the anniversary date

If you forget to index on the anniversary date, you can still request it later. However, the retroactive effect is limited:

• Brussels and Wallonia: indexation only takes effect for the 3 months preceding the written request
• Flanders: the general 5-year prescription applies, but retroactive effect is also generally limited

The months between the anniversary date and the written request are lost permanently. This is why timely notification is essential.

Regional specifics

Brussels-Capital Region

The Ordinance of 27 July 2017 confirms the annual indexation rule. EPC restrictions may limit or block indexation for properties with poor energy labels.

Wallonia

The Decree of 15 March 2018 applies the same annual indexation rule with similar EPC restrictions for labels E, F and G.

Flanders

The Flemish Housing Rental Decree of 9 November 2018 provides for annual indexation with less restrictive EPC limitations (only E and F labels affected).