What the cadastral income is
The cadastral income (CI) is a notional annual rental value assigned to each property by the Land Registry (Cadastre). Based on 1975 rental values, it has never been fully reassessed but is indexed annually (coefficient 2.1763 for 2026). The CI is the tax base for property tax and for personal income tax on rental properties. It does not reflect the current market rent.
The CI is fundamental to Belgian property taxation. Despite being based on 50-year-old values, it remains the cornerstone of the system. The annual indexation partially compensates for inflation but does not correct for changes in market values between different areas.
How to find your CI
You can find the CI of your property in several places:
- Purchase deed (acte d’achat): always mentions the CI
- Property tax notice (avertissement-extrait de role): lists the CI and the indexed CI
- MyMinfin portal: your personal tax profile includes all your properties with their CI
- FPS Finance cadastral office: upon written request
A 2-bedroom apartment in Brussels typically has a CI between EUR 700 and EUR 1,500. Indexed for 2026 (x 2.1763), this becomes EUR 1,523 to EUR 3,264. This indexed CI serves as the basis for property tax and, when increased by 40%, for income tax on private letting.
CI revision
The CI can be revised in certain circumstances:
- Major renovation: works that significantly alter the property’s rental value
- Extension or reduction: adding or removing rooms, floors or buildings
- Change of use: converting a shop to housing or vice versa
- New construction: the CI is set within the first year after completion
- Destruction: total or partial destruction reduces the CI
You are legally required to notify the FPS Finance of any renovation that increases the CI by at least 15%. Failure to declare may result in retroactive adjustment with interest. The notification is made via the Cadastre office.
A CI revision can work in your favour if your property has deteriorated or been reduced in size. Request a revision to potentially lower your property tax and income tax obligations.
Regional specifics
Brussels-Capital Region
The CI is a federal concept managed by the FPS Finance, not a regional matter. However, Brussels applies its own base rate (1.25%) to the indexed CI for property tax purposes. Brussels properties tend to have higher CIs reflecting higher 1975 rental values.
Walloon Region
Same federal CI system. Wallonia applies a 1.25% base rate. Rural properties in Wallonia often have lower CIs. The SPW Fiscalite uses the federal CI for property tax calculation.
Flemish Region
Same federal CI system. Flanders applies a 3.97% base rate to the indexed CI. Flemish properties in major cities (Antwerp, Ghent) tend to have higher CIs than rural areas.
Articles 471 to 504 CIR 92 (cadastral income), Royal Decree of 10 October 1979 (CI assessment rules) — Texts on Justel