A taxable property capital gain is reported in your annual personal income tax return, in the miscellaneous income section, for the year of the sale. It is taxed separately at 16.5% for a built property sold within 5 years. Exempt gains, such as your main residence or an inheritance, are not declared as taxable (Notaire.be, 2026).
Declaring a property capital gain only arises when the gain is actually taxable, which is the exception rather than the rule. If your sale is exempt, selling your main residence, or selling property you inherited, there is no taxable capital gain to report, because these are outside the speculative regime (Notaire.be, 2026). The declaration question therefore matters mainly for a built property resold within five years or building land sold within eight.
When the gain is taxable, it belongs in your personal income tax return for the income year in which the sale took place, entered under miscellaneous income (revenus divers). The tax authority then applies the separate rate: 16.5% for a built property sold within five years, and 33% then 16.5% for land within the relevant windows (Notaire.be, 2026). The rate is fixed and applies to the net gain, not your marginal income rate, so the calculation of the gain is where the real work lies.
Computing the gain follows a defined method. You take the sale price and deduct selling costs such as the agency commission, advertising and the mandatory certificates. From that you subtract your acquisition value, which you may increase by a flat 25% (or by the actual registration duties and notary fees), plus 5% for each full year you owned the property, and you can add documented renovation works carried out by registered contractors (Notaire.be, 2026). These uplifts frequently reduce the taxable gain substantially, and sometimes to zero.
Two practical pointers. First, keep every supporting document, the purchase deed, the sale deed, invoices for works and agency and certificate costs, because they justify the figures you declare. Second, if you are unsure whether an exemption applies, it is safer to confirm with your notary or accountant before filing than to omit a taxable gain, since the tax administration cross-checks notarial deeds. Get the classification right first, then the declaration is straightforward.
At a glance
- Only taxable gains are declared; main residence and inheritance are exempt (Notaire.be, 2026).
- Report in the annual return under miscellaneous income (revenus divers).
- Declare it for the income year of the sale.
- Rate: 16.5% for a built property sold within 5 years, separate from your income.
- Gain = sale price less selling costs, minus uplifted acquisition value.
- Acquisition value may rise by 25% (or actual costs) plus 5% per full year held.
- Keep purchase and sale deeds and all cost invoices as proof.