Belgium’s tax agency extends filing deadline to November 16

Belgium’s finance and tax agency, FOD Financiën, confirmed on October 29 that the affected October 31, 2026 tax-return deadline has been extended to November 16 because of the cyberattack-related outage.

The October 31 deadline was already an extension for returns declaring certain types of income, including income from sole traders and earnings from foreign companies. The affected returns would normally be submitted through Tax-on-web.

The extension covers all returns due to the Finance Ministry on October 31, including those specified-income returns. MyMinfin is Belgium’s main online portal for tax and financial affairs, through which such filings are normally made; Tax-on-web is the submission service for the affected returns.

Why the services went offline

Agency spokesperson Francis Adyns said the intrusion happened overnight on October 27–28 and was detected within hours, in comments carried by The Brussels Times. The agency announced the attack on October 28 and said it had suspended services to limit risks while specialists secured its systems.

Adyns said the attack was stopped before it could spread far enough to take control of applications or access data. Potentially infected components were isolated, taking MyMinfin—the agency’s main online tax portal—Tax-on-web and Biztax offline.

FOD Financiën said there were currently no indications of a data breach or compromised data. Investigators are continuing to examine possible data exposure.

The investigation

Belgium’s federal police and the Centre for Cybersecurity Belgium are involved in investigating who carried out the attack.

Authorities have not identified the attackers or disclosed how they gained access, The Record said. Earlier in October, the agency temporarily shut down many websites over an “international security issue”. Authorities have not publicly established a link between that shutdown and this attack.

Restoration and the new deadline

Adyns said the affected services must be restored in an isolated environment. That work takes considerable time because it must be done carefully to avoid new security risks. The agency said a large part of its other applications remained fully or partly available.

The Register said MyMinfin should be back online by November 16. That is an expected restoration horizon, not a guaranteed recovery date; the extension giving affected taxpayers until November 16 to file is confirmed.