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, security or the meat sector, you cannot simply do that without a prior check. You are legally required to verify first whether they have debts with the tax authorities, the ONSS/RSZ or Inasti/RSVZ. 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.
💡 What is the withholding obligation?
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 / FOD Financiën) and social security debts (ONSS/RSZ). Since 2026, it has also been extended to cover unpaid social contributions of self-employed contractors (Inasti/RSVZ). Because the exact scope and timing of this newest extension have been subject to change, always rely on the checkobligationderetenue.be platform for your specific contractor, it tells you precisely which withholding applies.
🚨 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.
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🏗️ Which sectors are affected?
The withholding obligation applies based on the type of work performed, regardless of your own line of business. It covers:
Construction and immovable works (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.
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, and for which type of debt.
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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.
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🔍 How to check before paying
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.
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.
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💶 How much to withhold?
Percentages are always calculated on the amount excluding VAT. VAT is paid in full to your contractor as normal.
Type of debt
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% to withhold (excl. VAT)
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Paid to
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Tax debts | 15% | SPF Finances / FOD Financiën |
Social security debts (ONSS/RSZ) | 35% | ONSS/RSZ |
Self-employed social contributions (Inasti/RSVZ) — new since 2026 | 15% | Inasti/RSVZ |
Maximum in case of multiple debts | 50% |
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ℹ️ Self-employed contributions have a threshold. The Inasti/RSVZ withholding only applies when the contractor's unpaid contributions exceed an indexed threshold (around €2,647 for reference year 2026). Below that amount, no withholding is due for this type of debt.
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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
💸 How to make the payments
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:
"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."
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⚙️ How to handle this in Accountable
You have one invoice but two payments. In Accountable, link both payments to the same expense so your bookkeeping stays correct.
⚠️ What if you have debts yourself?
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.
💡 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.
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Any questions? Our team is available in the chat 😊