Every owner of immovable property in Belgium — whether let or not — must report it in their annual PIT return. This covers properties located in Belgium and abroad.
Even a vacant property must be declared. The cadastral income (CI) of each property is included in the return, regardless of whether it generates rent.
The CI of your own home benefits from an exemption. Only properties other than your primary residence generate taxable income.
The method of taxation depends on the identity of the tenant and how they use the property.
| Situation | Taxable base | PIT code |
|---|---|---|
| Let to an individual (private) | Indexed CI × 1.40 | 1106 |
| Let to a company / professional | Actual rent − 40% (capped) | 1109 |
| Not let / second home | Indexed CI | 1106 |
| Property abroad (let) | Gross rental value − 40% | 1130 |
If your tenant uses part of the property for professional purposes, even a home office, the professional part will be taxed on actual rent. The lease must state the split.
This is the most common case. Your tenant uses the property as a residence, with no professional activity.
Pierre owns a flat in Ixelles. CI: €1,200. Actual rent: €950/month.
Taxable income = 1,200 × 2.1016 × 1.40 = €3,530
Pierre is taxed on €3,530, while he receives €11,400/year. The tax advantage is substantial.
In the 50% bracket, the additional tax is approximately €1,765/year — i.e. €147/month on a rent of €950.
When the tenant is a legal entity, the owner is taxed on the gross actual rent, reduced by a flat-rate allowance of 40% (capped).
Sophie lets an office to an SRL for €1,500/month. CI: €800.
Flat-rate (40%) = €7,200 · Taxable income = 18,000 − 7,200 = €10,800
That is double the tax compared to letting to an individual (≈ €5,260).
If the rent is excessive, the tax authority may reclassify the surplus as a benefit in kind. Make sure the rent is in line with market rates.
Here is how to declare your rental income in Tax-on-web.
Gather your documents
Assessment notice, current leases, rent statement.
Identify the CI of each property
Available on your assessment notice or via MyMinfin.
Non-indexed CI — the tax authority indexes automaticallyDetermine the correct PIT code
Individual → 1106. Company → 1109. Foreign → 1130.
Section III — Income from immovable propertyFill in the amounts
Code 1106: non-indexed CI. Code 1109: gross annual rent + benefits.
Review and submit
Tax-on-web calculates the indexation and the increase automatically.
Confusing indexed and non-indexed CI
Enter the non-indexed CI. The tax authority indexes automatically. Entering an already indexed CI = double taxation.
Forgetting the private/professional split
If your tenant carries on a professional activity, the professional part goes under code 1109. The lease must specify the split (e.g. 70/30).
Failing to declare a vacant property
A vacant property remains taxable on its CI. Exception: uninhabitable property → request for withholding tax reduction.
The FPS cross-references lease registrations with PIT returns. A registered but undeclared lease almost automatically triggers an audit. Surcharges: 10% to 200%.