The cadastral income is not what your property earns: it is a notional annual net rental income, meant to represent what the home could have earned in a single year under the 1975 rental market conditions. This reference figure, old and theoretical, remains the key to several Belgian property taxes.
How it is determined
The cadastral income is set by the Measurements and Valuations Administration of the FPS Finance (the former land registry). For a home, it rests on physical characteristics: floor area, number of rooms, comfort, location, compared with reference plots from that period.
The resulting value is expressed in euros and corresponds, by construction, to the 1975 rental market - the year of the last general revaluation. It has never been recalculated across the board since. This is why two properties that are comparable today can carry significantly different cadastral incomes, depending on the state of the local market in 1975 and the conversions declared since.
The annual indexation
The base cadastral income stays frozen, but each year an indexation coefficient published by the FPS Finance is applied to it. It is the indexed cadastral income that actually serves to calculate the taxes. It therefore rises mechanically every year, without the property changing.
What it is used for
Two main uses:
- The property tax (onroerende voorheffing): this annual regional tax is calculated on the indexed cadastral income. This is its most common use.
- Personal income tax: depending on the use of the property (own home, second residence, rented to a private individual or to a professional), the cadastral income may factor into the taxable income. The rules differ from case to case and evolve over time.
It also serves as a reference for various derived schemes (reductions, exemptions, eligibility conditions for certain benefits).
What you must declare
A new construction, an extension or a significant conversion (converting an attic, adding a bathroom, an extension) change the characteristics of the property: they must be declared to the FPS Finance, which recalculates the cadastral income. Failing to do so exposes you to a retroactive adjustment. Conversely, lasting deterioration may justify a downward revision, on request.
The link with market value
The cadastral income is disconnected from current prices: it says nothing about what your property is worth today. For that, the recent transactions in your municipality are what count, not a 1975 scale. The two figures answer two different questions - one sets your taxes, the other your price.