A closer look at commercial rent: determination, indexation and revision

Imagine: you are about to sign a commercial lease agreement. The location is right, the property feels right, the commercial plans are ready. And then the rent comes up: not just the amount, but also the small print. Will that rent increase every year? And can a rent that seems correct today be adjusted tomorrow? In this third contribution in the series on commercial leases, NOMA clarifies the rules surrounding rent, focusing on the different types, the possibility of rent indexation and rent review.

Fixed rent, turnover rent or a well-considered combination

The rent is rarely just a figure: it is the result of negotiations, expectations and sometimes also efforts. That is precisely why the legal framework surrounding it is so important. In general, there are three options for the rent in commercial leases:

#1. The most traditional formula remains the fixed rent. The parties agree on an amount that is deemed to reflect the normal rental value of the property. This amount is independent of the tenant's performance. For many entrepreneurs and owners, this offers peace of mind and predictability: you know where you stand, today and tomorrow.

#2. In addition, there is turnover-based rent, whereby the rent is linked in whole or in part to the tenant's turnover. This arrangement is particularly common in shopping centres, pop-ups or new retail concepts. If the business is doing well, the rent follows suit. If turnover lags behind, the rent adjusts accordingly.

#3. In practice, a combination of both is often chosen. A fixed basic rent, supplemented by a percentage of the turnover. This allows the landlord to maintain a minimum income, while the tenant retains flexibility. Such formulas do require clear agreements, including what exactly is considered turnover and how that turnover is determined.

Questions about commercial leases? In February and March 2026, NOMA is organising two live seminars in Brussels and Bruges. Leave your details here and we will be happy to keep you informed.

Rent indexation: not automatic, but a conscious choice

A persistent misconception is that commercial rents are automatically indexed. This is not the case: rent indexation is only possible if it is explicitly included in the lease agreement via an indexation clause.
 

Please note: indexation is not a free-for-all | If an indexation clause is included, the law imposes strict limits. The indexed rent may never exceed the result of the statutory formula, based on the health index:  

basic rent x new index figure / initial index figure.

The parties may agree on a more lenient arrangement, for example by setting a ceiling or using an adjusted formula, but never a stricter one.

Revision of the rent for commercial leases: the legal safety net

The rent for long-term commercial leases is not fixed for nine years. As a counterbalance to the legally required minimum term, the law provides for a mandatory option to have the rent revised.

In concrete terms, each party may request a review of the rent at the end of each three-year period. This is only possible if the normal rental value of the property has increased or decreased by at least fifteen per cent due to new circumstances. In that case, the court may adjust the rent, either upwards or downwards.

This right to review the rent is an integral part of the legal balance of commercial leases and cannot be excluded by contract. It therefore applies automatically, even if it is not provided for in the contract.

In commercial tenancy law, too, the legislator seeks to strike a balance between contractual freedom and protection. There is room for customisation, but within clear legal boundaries.
 

Rent as a legal balancing act in commercial leases

For both the tenant and the landlord, the rent is central to the commercial lease agreement, with room for customisation within a clear legal framework regarding indexation and rent review. A carefully constructed commercial lease agreement translates that framework into clear agreements, tailored to the property and the business that is building its clientele there.

Are you unsure about the determination or evolution of the rent? Or do you have questions about a current or future commercial lease? NOMA's solicitors will be happy to review your situation with you, with legal precision and an eye for the commercial reality of both parties. Please contact us.

In February and March 2026, NOMA will also be organising two live seminars on commercial leases, in Brussels and Bruges. Leave your details here and we will be happy to keep you informed.