Yes. Since the reform of 2021, a Belgian resident must declare any foreign property, including a Spanish second home, in the Belgian personal income tax return. A cadastral income (revenu cadastral) is assigned to it, and under the Belgium-Spain tax treaty it is exempt with progression, so it can still raise your Belgian tax rate (SPF Finances, 2026).
For years, foreign second homes were declared in Belgium on a different basis from Belgian ones, which the European Court found discriminatory. The Belgian law of 17 February 2021 fixed this by attributing a Belgian-style cadastral income (revenu cadastral) to immovable property abroad, putting a Spanish villa on the same footing as a Walloon one. Belgian residents are taxed on worldwide income, so the foreign property must appear in the annual return (SPF Finances, 2026).
Two obligations follow. First, a reporting duty: owners of foreign property had to declare it so the administration could set a cadastral income, and any new acquisition or sale of a foreign property must be reported to the competent administration (the Administration Mesures et Evaluations) within a short deadline after the event. Second, an annual declaration duty: the (non-indexed) cadastral income goes in Section III of the personal income tax return, with the country and amount specified so the correct treatment is applied (SPF Finances, 2026).
Now the reassuring part, and the counter-intuitive one. Because Belgium and Spain have a double taxation treaty, the taxing right on the property sits with Spain. Belgium therefore applies exemption with progression (exoneration avec reserve de progressivite): you pay no Belgian income tax on the Spanish home itself, but its income is counted when Belgium works out the marginal rate applied to your other income (SPF Finances, 2026). So declaring it rarely creates a direct Belgian tax bill, yet failing to declare it is still a genuine breach.
The taxable base for a built property is the indexed cadastral income increased by 40%, the same formula used for Belgian property (Wolters Kluwer, 2026). Easyhome flags this obligation early so buyers are not caught out at their first return after completing in Spain.
At a glance
- Rule: a Belgian resident must declare a foreign second home, including in Spain (SPF Finances, 2026).
- Basis: a cadastral income (revenu cadastral) is assigned to the foreign property since the 2021 reform (law of 17 February 2021).
- Where: Section III of the personal income tax return, stating the country and amount.
- Reporting: acquisition or sale of a foreign property must be reported to the administration within the set deadline.
- Tax treatment: Belgium-Spain treaty means exemption with progression, so no direct Belgian tax but it can raise your rate (SPF Finances, 2026).
- Base for built property: indexed cadastral income increased by 40% (Wolters Kluwer, 2026).