Belgian rental income tax calculator
How much tax do you pay on rental income from Belgian property? It depends on three things: the cadastral income (KI) of the property, your municipality, and — crucially — what your tenant does with the property. If you rent to a private tenant who lives there, you are not taxed on the actual rent but on the indexed cadastral income increased by 40%. If your tenant uses the property professionally, the actual rent is taxed and the bill is often several times higher.
This calculator covers all four regimes using the official figures for income year 2025 (assessment year 2026), including the municipal surcharge of each of Belgium’s 565 municipalities.
As stated on your property tax bill (aanslagbiljet), before indexation.
Where you live determines the municipal surcharge — not where the property is.
Where you live determines the municipal surcharge — not where the property is.
Proproll tracks the rent and costs of every property all year round, so your tax return is ready in minutes.
Start your 60-day free trialHow is Belgian rental income taxed?
For a private tenancy the formula is: KI × indexation coefficient (2.2446 for income year 2025) × 1.40. That amount is added to your other income and taxed at your marginal rate — the rate of your highest tax bracket (25%, 40%, 45% or 50%). On top comes the municipal surcharge, an extra 0% to 9% of the income tax due, depending on your municipality.
An example: an apartment with a KI of €1,000 in a municipality with a 7% surcharge, rented to a family. The taxable base is €1,000 × 2.2446 × 1.40 = €3,142. At a 50% marginal rate you pay €1,571 federal tax plus €110 municipal surcharge: roughly €1,681 per year — regardless of the rent you actually receive.
The four scenarios: your tenant’s use decides everything
Private: your tenant uses the property exclusively as a home. You are taxed on the indexed KI + 40%, not on the actual rent. By far the most favourable regime.
Professional: your tenant deducts (part of) the rent as a business expense — an office, practice or shop. You are taxed on the actual rent minus a 40% cost allowance, capped at two thirds of the revalued KI (revaluation coefficient 5.63 for income year 2025). The result can never be lower than under the private regime.
Mixed: your tenant lives and works in the property. With a registered lease that fixes the split, each part is taxed under its own regime. Without that split in the lease, the entire rent can be taxed as professional — an expensive omission.
Furnished: with furnished lettings part of the rent is movable income (for the furniture). Unless the lease says otherwise, the legal 60/40 split applies: the immovable part follows the KI regime, the movable part is taxed separately at 30% after a 50% cost allowance.
Why professional use costs so much more
Take the same apartment (KI €1,000, 7% surcharge, 50% marginal rate) with an annual rent of €12,000. Privately you pay about €1,681. Professionally the base becomes €12,000 minus the capped allowance of €3,753 = €8,247, or about €4,412 in tax — more than two and a half times as much. Always check what your tenant does with the property and what the lease says.
What this calculation leaves out
The calculator gives an indicative estimate for a natural person with Belgian property. It does not account for mortgage interest deduction, the tax-free allowance, the marital quotient or other personal elements of your return. Foreign property, letting through a company and usufruct structures are out of scope. For conclusive advice, consult an accountant or tax adviser.