Tax-on-web: filing your Belgian IPP online without picking the wrong code
Tax-on-web (via MyMinfin) is Belgium’s online personal income tax filing service. In 2026: paper by June 30, online by July 15. Every amount goes behind a four-digit code — and several benefits depend on your region.
Access and deadlines
Log in on MyMinfin with itsme or your electronic ID card. For assessment year 2026 (2025 income), the paper return was due June 30 and the online return July 15. Many taxpayers receive a simplified return proposal: check it line by line instead of accepting blindly — non-prefilled benefits (service vouchers, annuities, donations) rarely add themselves.
How the codes work
The Belgian return is organized in frames, and every amount goes behind a four-digit code: the left column (codes starting with 1) for the first filer, the right one (codes starting with 2) for the spouse. Example: filer 1’s withholding goes to code 1286, the spouse’s to 2286.
Watch out for benefits that became REGIONAL: service vouchers go in Wallonia to code 3366 (as a NUMBER of vouchers), in Brussels to 3364 (as an amount) — and give no benefit at all in Flanders since 2025. Alimony paid goes to frame VIII, code 1390, for its TOTAL amount (the administration applies the 70% deductible share itself).
Every code, ready to copy
Our “Belgian IPP” flow turns your answers into a list of exact codes with their amounts — including the regional subtleties — to copy into Tax-on-web.
Frequently asked questions
I missed the deadline: what happens?
File as soon as possible anyway: a late return risks penalties (surcharges, or even ex-officio taxation based on what the administration knows), which are almost always cheaper than a prolonged failure to file.
French resident working in Belgium: does Tax-on-web concern me?
Yes in most cases since 2012: without the old cross-border regime, your Belgian salary is taxed in Belgium — non-resident return (form 276.2) — then declared in France as exempt with a progression clause.