Understanding rent indexation for commercial leases in Belgium

Renting a commercial space in Belgium comes with its own set of rules and regulations, especially when it comes to rent indexation. Whether you’re a landlord or a tenant, understanding these nuances is crucial to ensure a smooth leasing experience.

Artem Gavrysh

Can you index the rent?

When it comes to commercial leases in Belgium, rent indexation isn’t always a given. Indexation is only possible if it’s explicitly mentioned in the rental contract. This means that as a landlord, you cannot index the rent unless it’s provided for in the lease agreement. This rule is consistent across all three regions: Flanders, Brussels, and Wallonia.

Legal formula for indexation

Landlords don’t have the freedom to choose any indexation formula they prefer. The law dictates the maximum indexation permissible. The basis for this calculation is the health index, which is a specific measure used in Belgium to adjust public wages, social benefits, and some rents to the cost of living.

Furthermore, the law mandates that rent can only be indexed once a year. This adjustment can only be made on or after the anniversary of the lease’s commencement date.

Brussels: A special case

If the rented property is located in the Brussels-Capital region, the rules deviate slightly. A temporary limitation on indexation is currently in place in Brussels. There’s a distinction in indexation for rental contracts that came into effect before July 31, 2021, and those that started after.

In Brussels, the consumer price index, excluding energy components, is considered for indexation. This means that prices of electricity, natural gas, butane, propane, liquid fuels, solid fuels, and motor fuels are excluded from the calculation.

Why is indexation important?

Rent indexation is a mechanism that ensures that the value of the rent keeps pace with inflation or other economic factors. For landlords, it ensures that the rental income maintains its purchasing power over time. For tenants, while it might mean a slight increase in rent, it also provides predictability, as they know the basis on which their rent might increase.

Things to consider

1. Clear contract: Always ensure that the rental contract clearly mentions the terms related to rent indexation. Both parties should understand and agree to these terms before signing.

2. Stay updated: Economic factors and regulations can change. It’s essential for both landlords and tenants to stay updated on any changes in the laws related to rent indexation, especially if the property is in Brussels.

3. Seek expert advice: If you’re unsure about the terms of indexation or how to calculate it, consider seeking advice from a real estate expert or legal professional familiar with Belgian property laws.


Rent indexation might seem like a complex topic, but with a clear understanding of the rules and regular updates, it can be easily managed. Whether you’re a landlord looking to ensure your rental income keeps pace with economic changes or a tenant wanting to understand potential rent increases, being informed is key.