Withholding obligation for construction and real estate, checked automatically

Article 30bis of the law of 27 June 1969 on social security for workers, covering immovable works and ready-mix concrete deliveries.

Since the Program Act of 22 December 2023, self-employed social debts (NISSE) are also taken into account.

The law of 15 May 2024 on social criminal law tightens penalties for missing declarations, missing withholdings or missing payments.

The withholding obligation is not an annual formality but a check per payment. What counts is the day you pay your supplier or sub-supplier. If they have social security debts at the NSSO or NISSE on that day, you withhold 35 percent of the invoice amount excluding VAT. Tax debts at FPS Finance add another 15 percent. Both administrations together can never claim more than 50 percent of the invoice.

On a construction site that situation shifts constantly. A sub-supplier who was debt free in March can have an outstanding NSSO contribution in May. Checking only at the start of the project means paying blind for the rest of the year. That is why Checkplicht works with a cadence: pick an interval from daily to every 30 days and every supplier in your file is automatically re-checked at the source.

For works in immovable property there is also the works declaration. The supplier declares the contract to the NSSO in advance and lists its sub-suppliers. Declaration and withholding are two separate duties: a correct declaration does not release you from checking at every payment.

If a debt is found, you split the payment. The withheld part goes straight to the NSSO and, where applicable, to FPS Finance. The remainder goes to your supplier. If you do not, you risk an administrative fine equal to twice the amount you should have withheld, on top of joint liability for the debt itself.

Checkplicht does not execute the payment. We show the exact percentage and amount and hand you over to the official application checkinhoudingsplicht.be, where the government supplies the correct payment details and structured reference. The payment therefore always stays at the source.

Your supplier can present a certificate limiting the withholding when the debt is lower than the calculated amount. In that case you withhold only the amount on the certificate. Keep it together with the check certificate; Checkplicht archives every certificate automatically with date, time and result.