Belgium’s Federal Public Service Finance said on Wednesday, October 28, that a cyberattack was disrupting its digital services, and it took the MyMinfin tax portal and several other online services offline as a precaution. The agency, known in Dutch as FOD Financiën and in French as SPF Finances, said it had so far found no indication that personal data had been breached or stolen. It also said it would extend some tax filing deadlines affected by the outage. None of the reports reviewed names the attacker, describes the type of attack or says when services will return.

What the agency said

Euronews, reporting on October 28, said the agency described its digital services as disrupted by a cyberattack. MyMinfin, the online portal where individuals and businesses manage tax returns and other financial documents, was temporarily taken offline together with several other services while officials investigate and secure their systems. The agency said there had so far been “no indications that anyone’s personal data had been breached or compromised,” according to Euronews, and that the investigation was continuing.

A French-language wire report from the Belga news agency, published the same day, gives more of the agency’s wording. It says MyMinfin and several other services were made temporarily inaccessible as a precaution, and that the measure limits risks and allows the necessary technical work. In a statement carried by Belga, the agency said it was following the situation closely and doing everything it could to restore the affected services as quickly as possible. It also said nothing indicated that data had leaked or been stolen.

All of these statements come from the agency itself. No official or spokesperson is named in the Euronews, Belga or Brussels Times reports. The other services that were taken offline are not identified, and ITdaily, a Belgian technology site, reports that several systems were down for an indefinite period with no end date given.

The deadline question

The outage landed near a filing date. According to the Brussels Times and ITdaily, tax returns containing specific income were due on October 31. Euronews says the agency would extend some upcoming filing deadlines affected by the disruption, with new dates to be announced, and Belga says the extra time applies to returns with certain types of income. The Brussels Times reports that affected filers will get a sufficient extension, and that the new deadline will be announced as soon as possible. No source reviewed gives a new date.

OECCBB, a Belgian professional body for accountants, says in an undated post that the principle of an extension has been agreed but its length is still being negotiated. It asks that the new period start from the actual and stable restoration of services, that it be announced once rather than extended repeatedly, and that taxpayers face no penalty for unavailability they did not cause. It also proposes an automatic extension whenever the agency’s applications are unavailable.

The OECCBB post advises members not to keep retrying logins or to reorganize client files around an assumed deadline, and to prepare files offline. It asks members to log each outage with the date, time, service and a screenshot so the institute can bring concrete cases into the talks. The post says a large part of the agency’s applications still work, fully or partly. A separate post on a Belgian tax-practice blog says the agency asked for understanding and promised an update once services work normally again.

Phishing and the risk to filers

The OECCBB post also warns that fake emails in MyMinfin’s name had already been circulating in the preceding days. It tells members and their clients not to open links that arrive by email or text message claiming to come from the finance agency and to use official channels only. The post does not say whether the phishing is connected to the attack, and the timing alone does not show a link.

The deadline matters because of what late filing can cost. In July 2024, VRT NWS described the rules at the time: an administrative fine of €50 to €1,250, a tax increase of 10 to 200 percent that does not apply when the undeclared income is under €2,500, and a longer period in which the tax authority can check the return. Those were the 2024 rules as reported then, and Lens did not check whether they have changed. They help explain why the accountants’ body is asking for a clear, penalty-free extension.

How many people use the portal

MyMinfin handles a large volume of returns. VRT NWS reported in July 2024 that 2,305,738 electronic returns had been submitted through MyMinfin by that year’s deadline, according to the finance agency’s spokesperson, Francis Adyns. The agency expected about 7.4 million returns in total, of which roughly 4 million are completed automatically through the pre-filled return, and about 200,000 on paper. VRT noted that the figures do not add up exactly, and it offered no explanation.

VRT also reported that in 2024 the later October deadline applied to returns with specific income, such as those of the self-employed and people with professional income from abroad, and that the authority then expected about 1.4 million such returns. The 2026 reports do not define specific income or say how many returns are still outstanding, so the number of people waiting on the new date is unknown.

Earlier outages and attacks

The October outage is not the first time MyMinfin has been disrupted. RTBF reported on July 13, 2026, that technical problems at Tax-on-web had led the agency to extend the online filing deadline from July 15 to July 19, after MyMinfin became accessible only intermittently over the preceding days. The report gives no cause, and none of the October reports links that episode to the attack.

Belga reported in October 2023 that distributed denial-of-service attacks had hit the websites of the Royal Palace, the Prime Minister and the Senate on a Thursday. On the Sunday, the finance agency flagged a hacker attack on X, and by Monday around 4 a.m. the finance agency’s site was reachable again while the Senate’s was not. A message in English on some homepages referred to Belgian aid to Ukraine and to the promise to send F-16 fighter jets in 2025. The report does not say who published the message or claim responsibility.

In May 2021, Business AM reported that a very large distributed denial-of-service attack hit Belnet, the network that connects federal government services, along with research centers and universities. Tax-on-Web and MyMinfin were among the sites that had problems, and the Chamber of Representatives suspended much of its work. Belnet announced measures that appeared effective around 6:30 p.m., hours after the attack began. Unlike those episodes, the October 2026 reports do not say what kind of attack this is, so no comparison can be drawn about its method.

What remains unknown

The unanswered questions are the ones that matter most to filers and to security researchers. The reports do not say when the attack began, how the attackers got in, which services besides MyMinfin are down, whether any data was touched, or when the portal will return. The agency’s statement that there is no sign of a breach is an early assessment, described by Euronews as covering the period so far, and the investigation is continuing.

Lens analysis: taking MyMinfin offline before the full scope was known suggests the agency chose to contain the incident rather than keep services available, and the cost of that choice falls on filers with an October 31 deadline. The extension’s length and start date will show how the agency balances that cost, and any later statement on data will show whether the early assessment held.

All of the sources reviewed are dated October 28. The finance agency’s website returned a human-verification page when Lens tried to check it on November 1, so any later notice about restoration or a new deadline was not seen. Readers who need to file should check the agency’s official channels for current dates.

Sources

Image: 20180907 Finance Tower Brussels.jpg by Flocci Nivis, CC BY 4.0, via Wikimedia Commons. Illustrative photo; it does not show the events described.