Withholding obligation: what it is and how to check it
The Belgian withholding obligation requires you to verify, at every payment to a supplier, whether that supplier has social security debts with the NSSO or tax debts with the FPS Finance at that moment. If there is a debt, you withhold part of the invoice amount and pay it directly to the institution instead of to your supplier.
This page covers everything you need: who the obligation applies to, how to check it supplier by supplier, which rates apply, what to do when a debt is found and how to repeat the check at every payment round.
Who has a withholding obligation?
The obligation follows the nature of the work, not your own activity. If you have work carried out that falls under article 30bis or 30ter of the law of 27 June 1969, the check applies even if you are not a contractor yourself.
Construction and real estate
Immovable work: building, renovating, demolishing, installing, maintaining, plus the delivery of ready-mixed concrete. Every contractor paying a subcontractor checks in turn.
Cleaning
Cleaning buildings and building-related maintenance fall under article 30bis, including inside a wider facility management contract.
Meat sector
Article 30ter covers cutting, processing and packaging meat, with the same check and the same rates.
Security and surveillance
Security and surveillance services fall under article 30ter. With rotating staff and subcontractors the chain here is long.
Private individuals having work done purely for private purposes are outside the scheme. When in doubt, look at how the work is described on the invoice, not at your supplier's NACE code.
Checking the withholding obligation in four steps
The check itself takes less than a minute per supplier once you have the right details.
- 01
Collect the company number
You need the ten-digit Belgian company number, usually printed on the invoice. The VAT number is the same number prefixed with BE.
- 02
Check social security debts
The NSSO indicates whether there is a contribution debt at that moment. For self-employed suppliers without staff the check runs through the NISSE.
- 03
Check tax debts
Next to the social debt there is a separate tax withholding obligation, checked with the FPS Finance even when the NSSO gives a green light.
- 04
Keep dated proof
In an audit you must be able to show that you verified debts at the moment of payment. Keep the proof for at least five years.
How a check works in practice
Import your supplier list, check every company number, get a result and proof per supplier.
- 01Import Excel
- 02Live check
- 03Red or green
- 04Automatic notifications
suppliers.xlsxHow much do you withhold?
The rates are calculated on the invoice amount excluding VAT and paid directly to the institution, not to your supplier.
of the invoice amount excluding VAT, for a social security debt.
of the invoice amount excluding VAT, for a tax debt.
never more than half the invoice amount excluding VAT.
If the actual debt is lower than the amount to withhold, your supplier can request a certificate from the FPS Finance stating the exact amount. That certificate is valid for 20 days and lets you limit the withholding.
What is the risk of not checking?
If you pay the full invoice while a debt existed, you become jointly liable for your supplier's social security and tax debts. That liability can reach the total price of the work.
On top of the liability comes an administrative fine equal to twice the amount you should have withheld.
Penalties were tightened by the law of 15 May 2024 on social criminal law. Dated proof of the check per payment is your only defence in an audit.
What to do when a debt is found
A red result does not mean you must end the relationship. It means you split the payment.
- 01Calculate the amount to withhold on the invoice amount excluding VAT: 35 per cent for a social security debt, 15 per cent for a tax debt, 50 per cent combined at most.
- 02Pay that amount through the official NSSO or FPS Finance payment channel, with the correct reference.
- 03Pay the balance to your supplier and state the withholding explicitly on your payment or credit note.
- 04Keep the proof of the check together with the proof of payment, for at least five years.
How long is a check valid?
A check is a snapshot on the day of payment. A supplier that was debt-free last month can have a debt today. There is no validity of weeks or months.
If you work with the same suppliers and pay weekly or monthly, that means a recurring check per supplier per payment round. Advances and partial payments count too.
This is why many companies repeat the check automatically and get alerted as soon as a debt appears or a supplier's legal situation changes.
Check yourself or automate it?
Both approaches are valid. The difference is the time it takes and the risk of missing a payment.
Yourself via the official portals
- Free and always available.
- One supplier at a time, in two separate applications.
- You keep dated proof per payment yourself.
- No alert when a supplier's situation changes.
Automatically with Checkplicht
- Import your full supplier list from Excel and check everything at once.
- Social and tax checks combined in one result per supplier.
- Automatic re-checks at your own frequency, with an email when a withholding is found.
- An email when a supplier's name, status or legal situation changes, for example on bankruptcy.
- Proof of check per supplier and a monthly overview as pdf.
Seven days free, then from 9 euros a month.
Frequently asked questions about the withholding obligation
The withholding obligation per sector
Rules differ per sector. Read per sector which activities are covered and where things go wrong in practice.
Read more in the knowledge base
Deeper explanations per topic, with the legal texts and official procedures.
Official sources
- NSSO: withholding obligation and joint liability (article 30bis)
- FPS Finance: joint liability and withholding obligation
- NISSE: withholding obligation in the self-employed social status
- Crossroads Bank for Enterprises, public search
This page is informative and not legal advice. If you are unsure about a specific case, consult the official sources or your accountant.