Do I have to file a tax return?
Yes, in principle every resident must file — but many receive a simplified return proposal and then need do nothing if it is correct. For assessment year 2026 (2025 income) the deadlines are: on paper until 30 June 2026, online via Tax-on-web until 15 July 2026, and for those with complex or specific income (e.g. self-employed profits, foreign professional income) until 16 October 2026. If you get a simplified return proposal and it is correct, you need do nothing — it becomes final automatically. If it is wrong or incomplete, you must correct it by the deadline. Anyone with professional, foreign or complex income, or who gets no proposal, must file themselves. New since 2025: a first good-faith mistake no longer automatically triggers a tax increase.
📋 The rules
- In principle, every resident must file; many receive a simplified return proposal
- A correct proposal = do nothing; if wrong, you must correct it by the deadline
- Assessment-year 2026 deadlines: paper 30 June 2026, online 15 July 2026, complex income 16 October 2026
- Complex/specific income (self-employed profits, company director, foreign professional income): always file
- Correction after filing is possible once via Tax-on-web until 15 July 2026
- Since 2025: a first good-faith mistake no longer brings a tax increase
🔓 Exceptions
- Whoever gets a correct simplified return proposal need do nothing — it counts as filed
- Have specific income and a proposal? Request the later deadline from the FPS Finance before 15 July 2026
- Since 2025, a first good-faith mistake no longer automatically triggers a tax increase
⚠️ Penalties & fines
If you don't file or file late, the FPS Finance can issue an ex-officio assessment: the burden of proof shifts onto you, and it is up to you to show the amount is too high. On top can come a tax increase of 10% to 200% depending on severity and repetition, plus a fine of €50 to €1,250. The quiet trap is the simplified return proposal: if you don't correct a wrong proposal before the deadline, it simply becomes final — mistake included. A first good-faith mistake has carried no increase since 2025.
📎 Official sources
- FPS Finance · tax return →
- FPS Finance · after the return →
- ITAA · personal income tax return 2026 (deadlines) →
❓ Frequently asked
Do I have to file a tax return?
In principle yes, as a resident. But if you get a correct simplified return proposal, you need do nothing. If it is wrong, or if you have complex income, you must correct it or file yourself.
What are the deadlines for 2026?
For assessment year 2026 (2025 income): on paper until 30 June 2026, online via Tax-on-web until 15 July 2026, and until 16 October 2026 for complex or specific income, such as profit as a self-employed person.
What is a simplified return proposal?
A pre-filled return the FPS sends you if your situation is simple and known. If everything is correct, you do nothing. If something is off, you fix it before the deadline — otherwise the incorrect proposal becomes final.
Can I still correct my return after filing?
Yes: you can correct your return once via Tax-on-web, until 15 July 2026. After that you have to lodge a formal complaint with the FPS Finance, which is a considerably heavier procedure.
What do I risk if I'm late?
An ex-officio assessment (with reversed burden of proof), a tax increase of 10% to 200% and a fine of €50 to €1,250. A first good-faith mistake has no longer been penalised with an increase since 2025.
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