Submitting your tax return (MyMinfin / Tax-on-web).

Details

• Source: https://fin.belgium.be/nl/particulieren/belastingaangifte/indienen/belastingaangifte
• Tool: MyMinfin (Tax-on-web)

Summary

You file your personal income tax return via MyMinfin (Tax-on-web). Depending on your situation, you will receive:

• a simplified tax return proposal (in that case you usually don’t have to do anything except review it), or
• a standard tax return (which you must submit).

1) Before you start: do you have a simplified return proposal?

1. Go to MyMinfin (Tax-on-web).
2. Open your tax return or simplified return proposal.
3. Check the pre-filled data.
   1. Is everything correct and complete? Then you don’t have to do anything.
   2. Is something incorrect/incomplete? Then you need to modify the proposal.

2) Submitting via MyMinfin (Tax-on-web) (step-by-step)

1. Log in to MyMinfin (e.g., with eID or itsme).
2. Open your tax return and go through it section by section.
3. Add or correct information where needed (a lot is pre-filled).
4. Go to the summary.
5. Click Submit (only then is your return actually filed).

3) Key deadlines (tax year 2026)

• 30 June 2026 (passed): if you submitted by post (paper return or paper amendment form).
• 19 July 2026 (passed): if you used MyMinfin (Tax-on-web) (submit or modify the proposal).
• 31 October 2026: if you use MyMinfin and declare specific income (e.g., self-employed income, foreign professional income, …). Extended; originally this was 16 October 2026.

4) Late or not submitted: what now?

• Submit your return as soon as possible anyway.
• If you submit late or not at all, you risk a fine and/or a tax increase.
• In some cases, the tax authorities can issue an assessment ex officio (your tax is calculated based on information they already have).

5) Can you request an extension?

In exceptional cases you can request an extension if:

• your request is submitted within the original deadline, and
• there is force majeure or serious reasons (e.g., serious illness, theft/fire causing documents to be lost, …).

You can request this via an online form or by contacting the FPS Finance (you’ll typically need to provide your national register number, how you submit, and your justification).

6) Checking whether your return was received

• In MyMinfin, go to My Return and check the status.
• If you see that the return was received, everything is in order.
• If you don’t see that:
  • Check that you actually clicked Submit after the summary.
  • If you submit via an accountant: there may be a delay between the appointment and submission.
  • If you submit by post: processing/digitization can take several weeks.

7) Mistake discovered after submitting

Found an error afterwards? Depending on your situation, you may still be able to correct your return online or contact the FPS Finance.

Frequently asked questions

I can’t log in with my identity card (forgot PIN or card blocked). What should I do?

• Request a new PIN code from your municipality (takes a few working days), or
• activate itsme via your bank and log in with that.

Can someone else submit my return?

Yes. You can:

• grant someone in your network a mandate via the secure mandate system (both parties sign digitally), or
• have your accountant create a mandate and sign it.

Source

https://fin.belgium.be/nl/particulieren/belastingaangifte/indienen/belastingaangifte