Complete your tax return

Complete your tax return

It's that time of year again: your tax return will have come in the post (or, better still, your inbox). And, yet again, the search is on for all the documents you need in order to complete the form. Here, we tell you a few things that you certainly must keep in mind when completing your tax return.

Due date for submitting your return

Sending it on paper

If you still fill in a paper tax form, it must be in the tax office's letter box on or before 29 June 2017. The address where you need to send it is printed on the return itself. Send it using the envelope enclosed with the tax return form.

Online submission

online belastingaangifte invullen

If you use Tax-on-web to do your tax return, you have until 13 July 2017. If your accountant does it for you, you even have until 26 October 2017.


Don't leave it till the eleventh hour to fill your tax return in, and so avoid any nasty surprises.

Submitting your tax return: on paper or online?

Filling your tax return in online using Tax-on-web is by far the preferred method, since it offers a number of advantages.

  • You get more time to fill the return in.
  • A number of figures that the tax office receives electronically are filled in from the outset: property tax, salary and wages, pensions, replacement income, service voucher outlays, gifts, pensions savings and certain standing details concerning your credit. However, we still advise checking the captions for which figures come filled in, especially gifts and property tax.
  • Sending it electronically is simpler. You don't have to enter any codes, thus reducing the risk of error. The online help function and handy wizards help you fill in your return and calculate your tax liability.
  • If you enter certain details incorrectly or omit them, you'll get an error message on the screen straight away.
  • You immediately get an estimate of how much your tax rebate or supplement will be.
  • You can continue to refer to the return after it's been sent. Even if you've already sent it in, you can correct any errors or omissions yourself up till 13 July 2017 (once only).
  • The tax office will process your return quicker, so you'll also get your final assessment sooner.


Needed in order to log into Tax-on-web

  • Your electronic identity card, a card reader and the PIN for your eID.
  • If you don't have a card reader, ask the tax office to issue you with a token, which is a card giving you personal codes to access the secure government apps.
  • You can also log in with a one-off code via a government app, though, the first time, you have to log in on a computer using a card reader.

Needed in order to complete your tax return

We advise you to first gather this information together before you start with filling in the tax return.

  • The number of the bank account for any tax refund that may be due to you.
  • Full details of your income: salary slips, rental income, maintenance, pensions, etc.
  • Details of your occupational expenses (if you are not claiming the lump-sum figure).
  • Tax certificates for your mortgage loan payments and mortgage protection insurance (if it qualifies for tax deduction).
  • Tax certificates for 'green' loans taken out to finance energy-saving investments (from 1 January 2009 to 31 December 2011) such as for solar panels, a central heating boiler, floor, wall or roof insulation, or double glazing.
  • Documents vouching payments into pension schemes.
  • Documents vouching payments into long-term savings schemes.
  • Documents vouching child-minding costs (for children under 12 – 18 if they're seriously disabled).
  • Details of payments made to local employment agencies (PWA vouchers).
  • Details of payments made by your for services paid for using service vouchers.
  • Other items for which tax relief can be claimed, such as certificates of donations, roof insulation bills, expenses to protect your home against fire and break-in (only in Brussels) and profit-sharing certificates in recognised development funds.
  • Numbers of foreign accounts and life insurance policies.
  • Details of any prepayments made for assessment year 2017.
  • Details of maintenance payments you've paid.


You should keep all documents you use for filling in your tax return for a period of seven years.

Don't just copy the figures from last year's return!

It'll do no harm to use your previous return as a reference. You'll see what information you provided then and should not be forgetting this year. But do be careful: amounts can vary from year to year, and codes change as well.

Where to claim your tax reliefs

Mortgage loan (home loan) – section IX

There are significant changes to section IX this year as regards mortgage payments and individual life insurance policies, with the introduction of a number of extra captions and codes. These have come about due to the state reform, which requires the regions to apply a different tax relief to private home loans contracted in and after 2015 from that applying to older loans. If you took out your mortgage in 2015, therefore, and you're entitled to a housing bonus, you have to use the new codes (3360/4360 – 3361/4361).

The new codes come first, where the old housing bonus used to be.

Since 2015, it has not be possible to aggregate the various tax breaks, home loan savings and housing bonus. Each taxpayer can only claim up to the maximum once.
Find out more about tax relief for your sole own home (housing bonus):

Long-term saving for individual life insurance policies – section IX

In income year 2016 (assessment year 2017), payments eligible for federal long-term saving schemes are tax-deductible up to 2,350 euros  Long-term savings qualify for tax relief of 30% of the actual deposits or 705 euros for each person claiming the maximum. Enter your payments into the scheme in code 1353 (for men) or 2353 (for women) in the return.

The housing bonus and federal long-term savings can be combined but the aggregate maximum is then 2,350 euros. Note that, because you can claim more tax relief for the housing bonus, it's best to channel as much expenditure as possible under that heading.

Find out more about long-term saving.

Pension saving – section X

In income year 2016 (assessment year 2019), the maximum relief on pension saving payments is 980 euros. You get 30% relief on the amount paid in. In the return, enter the figures after codes 1361 (for men) or 2361 (for women).

You cannot claim tax relief on pension savings on top of the allowance for acquiring employer shares.

Pension savings at KBC

Further help

Information booklets are enclosed with returns in paper form. Guidance is also available on the tax office website.

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