Understanding the paper Belgian income tax return

You cannot miss it; it is the document that has little text and columns in red.

It resembles a lotto form, and just like a lotto form it will be scanned. Just seeing it is quite disheartening, with columns and codes to complete. It is all a question of putting the right number or X with the correct code. And you get these codes from the draft form.

The draft

This is where you start the draft to help you file your tax return. There are three (slightly) different tax forms for people who live in Brussels, in Flanders or in Wallonia, all in two or three languages. This is because some tax incentives or tax reductions, e.g. for mortgages, cheques-service, renovation etc are given by the regions. And separate tax returns help avoid unnecessary mistakes. Whether you receive a Brussels, Flemish or Walloon tax return depends on the region where you were registered with the commune on 1 January 2024. And if you live in a commune with language facilities, you can opt to receive your tax return in French rather than in Dutch. Around Brussels, that is in Drogenbos, Kraainem, Linkebeek, Rhode-St-Genèse, Wemmel or Wezembeek-Oppem.

You need to work out what income goes in what box and with which code and then you copy the codes and the information in the tax return. If you work as a freelancer, a self-employed professional or the director of a company, you also need “part 2” (Dutch/French). Note that there are no different models per region.

When you copy the codes on the tax return, a few suggestions from the taxman: 

• use a black or dark blue pen, 

• write within the blocks, in capitals and in clear digits. 

• don't put in any unnecessary mentions or even ‘nil’. 

• don't strike out mistakes, use correction fluid. 

• If you have to give more information, don't write it by hand, the scanners have difficulties with handwriting. 

The green page

If you want to attach any documents justifying deductions or tax credits, you should attach them to the green page. It has all your information, and it is scanned with the attachments. You aren't obliged to file these documents; you may just keep them at home until the taxman specifically asks to see them. However, if you want to give additional information or if you have made a calculation of allowable expenses, I suggest that you attach a printed page with the information so that this information is on file immediately.

The explanation 

The tax authorities used to send a booklet explaining the tax rules with your tax return. They don’t do that anymore. You can find the explanation in Dutch or French online for each of the three regions (Brussels, Flanders and Wallonia).  

The envelope

When you have finished copying all the codes in the tax return, make sure that both spouses or partners sign it. And when you put it in the envelope, the address of the tax office goes behind the window.  

Do not forget the stamp. Postage isn't free.

Please note that you mustn’t drop the paper tax return in the letterbox of your local tax office. It must be mailed to the scanning centre in Jambes or in Ledeberg as indicated on the tax form. Fun fact: until about 10 years ago, tax returns were sent to the local office and on the last day, you could observe latecomers put their tax returns in the letterbox on the night of 30 June.

The taxman sends a Tax Proposal

Over half of all taxpayers do not have to file a tax return. The taxman already has all the information that they would just copy in their tax forms. This is the case for pensioners who do not have a side job, people with an invalidity or unemployment allowance, students over 18 who have some income, e.g. from a student job; even employees who claim the deduction for a mortgage.

Instead, the tax administration sends them a Tax Proposal, they call it a “Proposal of Simplified Taxation”, but basically they are saying “this is the information we have and this is how we will tax you, do you agree?” 

In the Tax Proposal they send you a list of the information they have about you (identity, marital status, salary, pension, deductions, gifts, …) and they calculate how much the tax will be and whether you get a tax refund.  The first time it comes in the mail, but once you have filed a tax return online or you have activated your digital mailbox “my e-box”, you will find your Tax Proposal in your e-box usually in the second half of May.

More than half of all taxpayers will receive a Tax Proposal (see the model in Dutch / French / German). 

Always check the Tax Proposal 

Never take the Tax Proposal for granted. The taxman has been known to make mistakes and some taxpayers have then missed out on tax rebates.  

Do not assume that the tax authorities do always know everything or always get it right, especially if there have been changes in your income or family situation in the course of 2023, such as the birth of a child.  A good tip: compare last year’s tax return with the Tax Proposal. If there are codes on one that are not on the other, that should set off an alarm bell. 

Start by checking the information in box II of the tax return about your family situation. Did you get married last year, did you move in together last year or did you get divorced? Was a child born or added to the family, or is one of your children no longer a dependant? Changes in the family situation can have an important effect on the final bill, but the tax authorities are not always aware of it.

This also applies to some specific categories of income and expenses. For example, the tax authorities are not automatically aware of real estate income, such as the rent from a second residence. If you have a second job as a self-employed, they are not aware of that income. Employees who want to deduct their actual business expenses must prove these – that is information that is not already in the Tax Proposal. And check carefully that all the gifts you made are listed. These are just some examples of the information that may be missing.

What the taxman does not know is that you have overseas bank accounts or insurance policies or that you receive maintenance payments. Moreover, you may want to recover some withholding tax on dividends. In these situations you should always file a tax return.

How do I correct the Tax Proposal?

If you find that a correction must be made, the easiest way to do this is by logging in to Tax-on-web and making the corrections. Do not forget that both spouses or partners must sign and send the corrected Tax Proposal as you would sign an actual tax return on Tax-on-web.  If you have received a Proposal in the mail, there is a form attached to report the corrections. You must return it to the Federal Public Service Finance. 

Corrections must be reported by 30 June (or online before 15 July). If the information is correct, the definitive tax bill will follow soon.

More from our 2024 income tax guide

1. When do I need to file my Belgian income tax return?
2. Belgian income tax returns for families
3. Online or on paper?
4. Filing online
5. Understanding the paper tax return
6. Checklist: What documents do you need?
7. The return in detail
8. Belgian income tax: There's nowhere to hide
9. A guide to cross-border taxation
10. Help! Where to get assistance with your tax return
11. Understanding your Belgian income tax bill
12. How do I appeal?

• This guide was written by Marc Quaghebeur, an international tax lawyer at Cabinet DAVID. It is a general introduction based on current understanding of the law. It is not to be taken as a suitable alternative for individual advice. If you have a question, you can contact him by clicking on his name.