In Belgium

Rental value is the reference concept for determining a fair rent. It does not correspond to the cadastral income (a 1975 tax fiction) but to the real market price.

Rental value depends on multiple factors: location, surface area, property condition, EPC label, equipment (parking, terrace), and local market conditions.

The indicative rent grid (Brussels, Wallonia) provides a standardised estimate. For a more precise evaluation, a property expert can be commissioned.

In a triennial review, rental value is the central element: the landlord or tenant must prove it has changed by more than 20%.

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Good to know
Rental value evolves over time. A gentrifying neighbourhood sees values rise. Conversely, a new airport or factory can cause them to fall. That is why the triennial review exists.

Practical example

A 2-bedroom apartment in Saint-Gilles (Brussels), 80 m2, EPC C, 2nd floor with terrace. The indicative grid shows 900-1,100 EUR/month. The landlord sets rent at 1,000 EUR. After 6 years, the neighbourhood has developed and similar properties now rent at 1,250 EUR. The rental value has risen by 25% — the landlord can request a review.