Where do I find my supplier's company number?

On the invoice, in the contract or through the public search of the Belgian Crossroads Bank for Enterprises. The company number has ten digits and equals the VAT number without the BE country code.

How long is a check valid?

A check applies to the payment you perform it for. There is no validity of weeks or months: for the next payment you check again.

What if my supplier does have debts?

You withhold the applicable percentage of the invoice amount excluding VAT and pay it directly to the NSSO or the FPS Finance. You pay the remainder to your supplier, stating the withholding.

Does the obligation apply to self-employed suppliers without staff?

Self-employed suppliers can have social debts too. For them the social check runs via the NISSE instead of the NSSO. The tax check is the same.

What is the difference between article 30bis and article 30ter?

Article 30bis governs the withholding obligation for immovable works and related activities. Article 30ter extends the same logic to certain activities in other sectors, including meat processing.

Am I covered as a client without construction activity?

Yes. The obligation depends on the nature of the works, not on your own activity. If you have immovable works carried out, the check applies even if you are not a contractor.

What is the risk of not checking?

You can become jointly liable for your supplier's debts up to the value of the works, and you risk a surcharge on the amount you should have withheld.

Do I need evidence for every invoice?

You must be able to show that you checked at the moment of payment. A dated check certificate per payment is the simplest way to do that.

Check the withholding obligation: how do you verify a supplier?

You check the withholding obligation by looking up each supplier's Belgian company number and verifying whether, at the moment of payment, that supplier has social security debts with the NSSO or tax debts with the FPS Finance. If there is a debt, you withhold part of the invoice amount and pay it directly to the relevant authority instead of to your supplier.

This page explains when to check, what you need, how to read the result and how to automate the check for all your suppliers at once.

Try 7 days free See pricing

What a check looks like

Import your supplier list, check every company number, get the result and a check certificate per supplier.

01
Import Excel
02
Live check
03
Red or green
04
Automatic notifications

Total

0

Compliant

0

Withholding

0

suppliers.xlsx

LeverancierKBONaamRSZFODStatus

0712.345.678Bouwwerken De Vos

·

0645.112.089Elektro Peeters

·

0598.221.004Dakwerken Janssens

·

0834.556.221Schilderwerken Aerts

·

0761.998.334Sanitair Vermeulen

·

Check a supplier in four steps

The check itself takes less than a minute per supplier once you have the right details at hand.

01
Collect the company number
You need your supplier's Belgian company number, ten digits, usually printed on the invoice. The VAT number is the same number prefixed with BE.
02
Check social security debts with the NSSO
The NSSO indicates whether the supplier has an outstanding contribution debt at that moment and whether you must withhold. For self-employed suppliers without staff, the check runs via the NISSE.
03
Check tax debts with the FPS Finance
Alongside the social debt there is a separate tax withholding obligation. You check that with the FPS Finance, even when the NSSO gives a green light.
04
Keep the result as evidence
Keep a dated check certificate per payment. During an inspection you must be able to show that you verified debts at the moment of payment.

What does the result mean for your payment?

No debts found

You pay the invoice in full to your supplier. Keep the dated certificate, because the result only applies to this payment.

Debt found, withholding required

You withhold the amount due and pay it to the NSSO or the FPS Finance. If you do not, you risk both the withheld amount and a surcharge.

What is the withholding obligation?

The withholding obligation is set out in articles 30bis and 30ter of the Belgian law of 27 June 1969. Anyone having works carried out that fall under those articles must verify, at every payment, whether the supplier has social security or tax debts.

The obligation applies to the client and to every contractor in the chain paying a subcontractor. It is not limited to construction: certain activities in cleaning, meat processing and security services are covered too.

If your supplier has a debt and you pay the full invoice, you become jointly liable for that debt. Withholding protects you against that joint liability.

How much must you withhold?

NSSO

35%

of the invoice amount excluding VAT, in case of a social security debt.

FPS Finance

15%

of the invoice amount excluding VAT, in case of a tax debt.

Maximum

50%

together never more than the invoice amount excluding VAT.

When the debt is lower than the withholding amount, a limited withholding can be enough. In that case request a certificate from the relevant authority or check with your accountant.

When do you have to check?

Before every payment. A check is a snapshot: a supplier who was debt free last month can have a debt today. The obligation also applies to advances and partial payments.

If you work with the same suppliers and pay weekly or monthly, in practice that means a recurring check per supplier per payment run.

That is why many companies repeat the check automatically and get notified as soon as a debt appears at one of their suppliers.

Check manually or automatically?

Both are valid. The difference is the time it takes and the risk of missing a payment.

Manually via the official portals

Free and always available.
One supplier at a time, in two separate applications.
You keep a 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.
NSSO, NISSE and the tax check combined in one result.
Automatic rechecks at your own interval, with an email alert when a withholding is found.
Check certificate per supplier and a monthly overview as pdf.

Try 7 days free

Seven days free, then from 9 euro per month.

Frequently asked questions about checking

Withholding obligation per sector

Rules differ per sector. Read which activities are covered and where things typically go wrong in practice.

Construction & real estate

Works in immovable property, renovation, electrical and concrete.

Cleaning

Professional cleaning and building maintenance services.

Meat sector

Cutting, processing and distribution of meat.

Security & surveillance

Guarding, monitoring and surveillance services.

Knowledge base FAQ Pricing

Official sources

This page is informational and not legal advice. If you are unsure about a specific case, consult the official sources or your accountant.