Belgian tax residence and annual returns: a guide for Greek residents

Every spring the Belgian tax return lands, on paper or in MyMinfin, and every spring the same questions arrive from Greek and other international residents of Brussels: must I declare my Greek rental income, my savings account in Athens, the apartment inherited from my parents? In June 2025 JuriSpectrum's founding partner addressed these questions at a seminar organised by the Greek Community of Brussels together with a Greek tax adviser. This note summarises the framework.

Who is a Belgian tax resident

Belgium taxes as residents the persons who have their domicile in Belgium or, failing that, the seat of their wealth there. Domicile is a question of fact: where you actually live, where your family is, where you work and organise your affairs. Registration in the national register of a Belgian commune creates a presumption of residence which the taxpayer may rebut; for married couples and legal cohabitants, the family home is decisive. A Greek national who moves to Brussels for work and settles here with his or her family is a Belgian tax resident from the day of arrival, whatever Greek registrations remain in place. Where both countries claim residence, the tie-breaker rules of the double taxation treaty settle the matter.

The annual return

Belgian residents file a personal income tax return (déclaration à l'impôt des personnes physiques) each year for the income of the previous calendar year. The return is filed online through Tax-on-web in MyMinfin, on paper, or through an authorised representative. For the 2026 exercise (income of 2025) the deadlines announced by the tax administration were 30 June for paper returns, 15 July for online returns and 16 October for online returns containing certain categories of income such as self-employed or foreign professional income. Many taxpayers receive a proposition de déclaration simplifiée, a pre-filled proposal; accepting it silently is a filing, and an incomplete one if it omits foreign items.

Worldwide income and the treaty with Greece

A Belgian resident is taxable on worldwide income. Relief from double taxation comes from the Convention between Belgium and Greece signed in Athens on 25 May 2004, which replaced the 1968 convention and applies to income from 2005 onwards. Its logic follows the OECD model. Income from immovable property is taxable where the property is located, so Greek rental income, and the notional income attached to a Greek holiday home, is taxed in Greece and exempted in Belgium, but with progression: the exempt income is taken into account to set the rate applicable to Belgian income. Employment income is generally taxed where the work is physically performed. Dividends and interest from Greek sources may be taxed in Greece at a limited rate and are taxed again in Belgium with a credit or deduction depending on the category. Each item must nonetheless appear in the Belgian return, in the boxes for foreign-source income, even where the treaty exempts it.

Foreign accounts, insurance and property

Three reporting duties are independent of whether any tax is due. First, the existence of any account held abroad, by the taxpayer, the spouse or minor children, at any moment during the year must be ticked in the return and the account details (holder, country) declared. Second, the account must be notified once to the Central Point of Contact (Point de contact central) of the National Bank of Belgium, at the latest when the return is filed; a single notification per account suffices for subsequent years. Third, foreign life-insurance contracts and foreign legal arrangements such as trusts or foundations are subject to their own declaration lines. Foreign real estate is now treated like Belgian real estate: the taxpayer must declare the acquisition of a property abroad to the administration, which attributes a cadastral income to it, and the property then appears in the return every year.

EU officials and other agents of the institutions

Staff of the European institutions are in a special position under Protocol No 7 on the Privileges and Immunities of the European Union. Their salaries and emoluments paid by the Union are subject to the Union's own internal tax and are exempt from national income tax. Moreover, an official who has come to Belgium solely to perform his or her duties is deemed to keep his or her tax domicile in the country of origin; the same applies to a spouse not separately engaged in a gainful occupation and to dependent children. In practice a Greek official who was resident in Greece on entry into service remains a Greek tax resident for Belgian purposes: the Union salary is not declared in Belgium, but Belgian-source income such as a rental property in Brussels is taxed in Belgium as non-resident income, and worldwide income other than the Union salary must be dealt with under Greek rules. Contract staff, seconded national experts, employees of private employers in the EU quarter and spouses with their own employment do not benefit from the deeming rule and are ordinary Belgian residents.

Common pitfalls

• Not filing at all because no Belgian tax appears to be due; the return is mandatory and the fines and increases for late or omitted filings are automatic.
• Forgetting a dormant Greek account, an e-banking account, or a joint account with a parent; every account counts.
• Declaring Greek rental income in Greece only, and omitting it from the Belgian return where it affects the progressive rate.
• Treating the deeming rule of the Protocol as extending to a spouse who works locally, or to periods before entry into service.
• Ignoring the property registration duty for an inherited Greek flat, or the reporting line for foreign insurance.

This article is provided for general information only and does not constitute legal advice. It reflects the law and the authors' views at the date of publication. For advice on a specific situation, please contact the firm.