You are having your office renovated, your building cleaned, or your business premises secured. The invoice arrives and you just want to pay for the services received. But for invoices from contractors in construction, cleaning or security, you cannot simply do that without a prior check. You are legally required to verify first whether they have debts with the tax authorities or the ONSS. If that is the case, you must pay part of the invoice directly to the State. This is called the withholding obligation, and in this article we explain everything you need to know to always stay compliant.
In certain sectors, you cannot simply pay a contractor's invoice without first checking whether they have tax or social security debts. If they do, Belgian law requires you to withhold a percentage of the invoice amount and pay it directly to the relevant public authority. This is called the withholding obligation.
This rule has existed for a long time for fiscal debts (SPF Finances) and social security debts (ONSS). Since 1 May 2026, it also covers debts related to a self-employed person's social contributions (Inasti/RSVZ).
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🚨 If you forget to check or withhold, you can be held jointly liable for your contractor's debts, up to the full invoice amount excluding VAT. You also risk a fine. |
The withholding obligation applies in these sectors:
Construction and renovation (contractor renovating your office, painter, electrician, plumber, etc.)
Cleaning (cleaning company for your premises, etc.)
Security and surveillance (security firm for your event or building, etc.)
Meat industry
If you are yourself a contractor and you subcontract work in one of these sectors, the obligation applies to you too.
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ℹ️ The checkobligationderetenue.be platform is the definitive source. By entering your contractor's company number, you will know with certainty whether the obligation applies. |
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✅ Strictly private work: no obligation. If you are having your personal home renovated as a private individual, you do not need to check or withhold anything. |
You must carry out this check twice:
At the signing of the contract
Just before each payment of an invoice (even if everything was fine at the start)
Here is how:
Go to checkobligationderetenue.be and enter the contractor's company number (found on the invoice or in the CBE/KBO).
The platform immediately shows whether there are debts and, if so, the percentage to withhold and the payment instructions.
Download the consultation certificate and keep it with the invoice. This is your proof in case of a tax audit.
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ℹ️ The certificate has a limited validity period. If you pay after the date shown on the certificate, you must consult the platform again before making the payment. |
Percentages are always calculated on the amount excluding VAT. VAT is paid in full to your contractor as normal.
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Type of debt |
% to withhold (excl. VAT) |
Paid to |
Tax debts | 15% | SPF Finances / FOD Financiën |
Social security debts (ONSS/RSZ) | 35% | ONSS/RSZ |
Self-employed social contributions (Inasti/RSVZ) — new since 1 May 2026 | 15% | Inasti/RSVZ |
Maximum in case of multiple debts | 50% |
Example: you receive an invoice for €2,000 excl. VAT (€2,420 incl. 21% VAT) and your contractor has tax debts.
15% of €2,000 = €300 to pay to SPF Finances / FOD Financiën
VAT = €420 paid normally to the contractor
Amount paid to the contractor = €2,120
You make two separate transfers:
The withheld amount to the relevant authority. The exact account number and payment reference are provided directly by the checkobligationderetenue.be platform after the check.
The remaining balance directly to your contractor.
Let your contractor know in advance that they will receive a reduced amount. A short message like this works well:
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"Hi [name], I have received your invoice and carried out the mandatory check via checkobligationderetenue.be before paying. The check shows there are [tax / ONSS / Inasti] debts. I am legally required to withhold [X]% and transfer it directly to [SPF Finances / ONSS / Inasti]. I am transferring €[amount] to your account and €[withheld amount] directly to [authority]. I attach the certificate as proof." |
You have one invoice but two payments. In Accountable, link both payments to the same expense so your bookkeeping stays correct.
If you work in one of the sectors concerned and you have outstanding debts, your clients will be required to withhold part of your invoices. You will therefore receive less than the invoiced amount, which can seriously disrupt your cash flow. To check your own situation:
Tax debts: MyMinfin, you can see pending amounts and any repayment plans.
ONSS/RSZ debts: your social insurance fund or the social security portal.
Inasti/RSVZ contributions: MyInasti or your social insurance fund to see if any quarters are outstanding.
If you cannot pay everything at once, both the Inasti and SPF Finances offer repayment plans. Contact them proactively: the sooner your debts are settled, the sooner your clients can pay you in full again.
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💡 Debts settled but clients are still withholding? Contact the relevant authority to request an update. Processing can take a few days. Once the system is updated, clients will be able to pay you in full again. |
Any questions? Our team is available in the chat 😊
Author - Valesca Wilms
As content marketing lead at Accountable Belgium, Valesca writes about freelancing, self-employment, and taxes based on her own experience as a freelancer.
Who is Valesca ?Thank you for your feedback!
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