In Belgium

Rent indexation is governed by regional legislation. Each Region — Brussels-Capital, Wallonia and Flanders — has its own rules, although the basic principle is identical: the landlord can adjust the rent once a year to keep pace with the cost of living.

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Good to know
Indexation is never automatic in Belgium. The landlord must expressly request it from the tenant, preferably in writing. Without an explicit request, the rent stays at the original amount.

The three Regions share a common rule: indexation can only occur once per rental year, at the earliest on the anniversary of the lease’s entry into force.

How it works

Indexation formula
Indexed rent = base rent x new health index / starting health index
  • Base rent: the rent agreed in the original lease (excluding charges)
  • New health index: the health index for the month preceding the lease anniversary
  • Starting health index: the health index for the month preceding the lease signing date

Practical example

Marc, owner of an apartment in Liege, signed a lease on 1 September 2023 with a base rent of 750 EUR/month. For indexation on 1 September 2024: 750 x 131.77 / 128.92 = 766.62 EUR.

Key considerations

EPC restriction in Brussels. Since 14 October 2022, landlords with an EPC label E, F or G in Brussels cannot index the rent. Label D is limited to 50%.

Retroactivity limited to 3 months. If the landlord forgets to request indexation, they can only claim retroactively for the 3 months preceding their written request.

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Warning
Indexation and rent review are two distinct mechanisms. The review modifies the base rent itself at the end of each triennial. After a review, future indexations start from the new base amount.