200,000 Belgians Didn’t File Taxes: Who They Are and the Risks They Face

Nearly 200,000 Belgians failed to submit their tax returns for assessment year 2025, according to data obtained by federal MP Niels Tas (Vooruit) from Finance Minister Jan Jambon (N-VA). The figures, reported by Het Laatste Nieuws, reveal a compliance gap of approximately 2.4% of all tax files, with young adults and residents of the Brussels-Capital Region disproportionately represented among non-filers.

Context: Who Must File?

Of Belgium’s roughly 7.5 million taxpayers, about 4 million receive a simplified tax proposal — a pre-filled return completed by the tax authorities. According to HLN tax expert Michel Maus, non-response to a simplified proposal is treated as acceptance, meaning these taxpayers cannot technically file late. The remaining 3 million Belgians must actively submit their returns, with standard filers facing a 19 July deadline and those with complex returns — including foreign income, self-employment, or those using accountants — having until 16 October.

For assessment year 2024, 179,111 out of nearly 7.5 million tax files were not submitted, a 2.4% non-filing rate. This represents an improvement from 2018, when nearly 228,000 Belgians (3.28% of taxpayers) failed to file.

Who Are the Non-Filers?

The data reveals two particularly vulnerable groups. The Brussels-Capital Region accounts for a disproportionately high share: 54,165 non-filers for assessment year 2024 — roughly a quarter of the national total — despite having only 1.25 million residents. By contrast, Antwerp province, with 1.9 million residents, has fewer than half as many non-filers.

Young people aged 18 to 24 are also heavily represented, with 30,579 non-filers for assessment year 2024 — a significant increase compared to 2016. This suggests a growing compliance gap among young adults who may be new to the tax system, unfamiliar with procedures, or facing precarious employment situations.

Penalties and Risks

Non-filers face escalating penalties through a process known as an “ex-officio assessment” (ambtshalve aanslag). “For a first offense, 10% of the amount due is added,” Maus explained. “If you fail to file again the next year, it becomes 20%. The third year it’s 30%, and so on.”

MP Tas warned that ex-officio assessments often fail to account for personal circumstances. “An ex-officio assessment often doesn’t take into account personal expenses such as childcare or donations, or a tax credit for dependent children,” he said. “People are thus punished again and have to pay extra money because they simply don’t understand the complex rules.”

Political Debate

The issue has sparked a political debate about tax system complexity. Tas, whose Vooruit party requested the data, argued that the government has made it harder for citizens to get help. “The FOD Financiën has abolished the fixed walk-in consultation days where people could get help at the tax office,” he said. “Now you have to make an appointment or request help by phone or online. That raises the barrier.”

A spokesperson for Finance Minister Jambon countered that “the FOD Financiën provides numerous initiatives every year to guide people even better,” while acknowledging that “it could be even simpler, and we want to continue focusing on a simpler tax return.”

Broader Context: IT Failures

The non-filing figures come amid broader concerns about the tax authority’s digital infrastructure. Just days before the 15 July digital deadline, the MyMinfin online platform experienced a major outage, leaving many taxpayers unable to log in or access Tax-on-web, as reported by HLN. The outage prompted an extension of the deadline to 19 July.

Separately, the Institute for Tax Advisors and Accountants (ITAA), representing 13,500 recognized accountants and tax advisors, has formally challenged the government over recurring IT platform failures, as HLN reported. ITAA chair Emmanuel Degrève stated: “The sector will no longer continue to endure the government’s IT errors.”

Analysis and Outlook

The declining overall non-filing rate — from 3.28% in 2018 to 2.4% in 2024 — suggests that increased digitalization may be helping improve compliance. However, the rising number of young non-filers and the concentration in Brussels point to structural issues requiring targeted policy responses.

With the October deadline for complex returns still approaching, and the political debate over tax simplification intensifying, the coming months will test whether the government can balance enforcement with the accessibility reforms that critics argue are urgently needed.

Reporting based on data from Het Laatste Nieuws, with additional context from HLN reporting on MyMinfin outages and ITAA challenges.