Dit artikel werd geüpdatet op 11 maart 2026.
The withholding requirement has been an important tool in the fight against social fraud in sectors such as construction, cleaning, security and meat for years.
Tot nu toe was je als opdrachtgever enkel verplicht om na te gaan of je (onder)aannemer fiscale of RSZ-schulden had. Vanaf mei 2026 (de exacte datum moet nog bevestigd worden) komt daar een nieuwe controleverplichting bij: ook de sociale bijdragen van zelfstandige (onder)aannemers (RSVZ) vallen voortaan onder de inhoudingsplicht.
What does this mean specifically for you as a business owner? In this article, we provide a clear overview of what the withholding requirement means today and what the expansion will look like starting in 2026.
What is the withholding obligation and when does it apply to you?
The withholding obligation applies to entrepreneurs operating in the following sectors and following activities perform:
- Works in real estate (such as construction, electrical engineering, cleaning and maintenance), with the exception of some specific activities from agriculture, horticulture and forestry;
- The delivery from ready-mixed concrete;
- Surveillance and/or monitoring services;
- Activities in the meat sector.
When you, as an entrepreneur, appeal to a (sub)contractor, you should check whether this (sub)contractor fiscal and/or social debts has. These are therefore debts to the tax authorities (e.g. corporate tax arrears) and debts to the NSSO (employee social security contributions).
If your (sub)contractor is effectively indebted, then you should forward part of the invoice directly to the NSSO and/or the tax authorities:
| Debt | Condition | Retention rate on the invoice | Forwarding to |
| NSSO debt | / | 35% | NSSO |
| Tax debt | Invoice < €7,143 | 15% | Tax |
| Invoice ≥ €7,143 + debt < 15% of invoice amount | Full amount on attestation | ||
| Invoice ≥ €7,143 + debt > 15% of invoice amount | 15% |
Via checkinhoudingsplicht.be you can easily check whether the (sub)contractor you are working with has fiscal and/or social debts and, consequently, whether or not the withholding obligation applies.
Penalty for non-compliance: joint and several liability for social and fiscal debts
Are you working with a (sub)contractor who has outstanding fiscal or social debts at the time of the agreement, the start of work or payment of the invoice? Then as the principal you are mandatory to create a withhold part of the invoice and by dumping to the NSSO and/or tax authorities.
Are you not doing this? Then you risk joint and several liability. This means that the government can sue you as a principal to pay (part of) your (sub)contractor's debts. This can be financially onerous: in the worst-case scenario you pay the invoice 2 times: once to the government AND once to your (sub)contractor.
Important: this liability does always limited to the amount for which you no proper withholding have done. But of course it is still a risk best avoided.
Uitbreiding vanaf mei 2026
Vanaf mei 2026 wordt de inhoudingsplicht verder extensive: also the social contributions that independent (sub)contractors owe to the RSVZ must be followed from now on.
Did your independent (sub)contractor more than €2,500 to unpaid social contributions? If so, you are required to 15% to withhold from the invoice amount and by dumping to the NSSO.
However, the withholding obligation for social contributions is irrelevant in the following cases:
- You are a private client;
- The payment deadline of social contributions has not yet expired;
- There is a installment plan that is properly observed;
- There are also NSSO or tax debts (Then only the existing withholding rules apply).
As with the existing withholding obligation, the principle of joint and several liability. This means that, as a principal, you can also be jointly liable for your independent (sub)contractor's overdue social security contributions, albeit limited to the amount for which you failed to make proper deductions.
Wat betekent dit voor jouw facturatie?
Vanaf mei 2026 moet je niet alleen fiscale en RSZ-schulden controleren, maar ook nagaan of je zelfstandige (onder)aannemer overdue social security contributions has. Check this via checkinhoudingsplicht.be at these 3 times:
- At the close of the agreement
- At the start of the work
- At the payment of the invoice
De overheid ondersteunt deze inhoudingsplicht voortaan met de vernieuwde Billretainment‑webservice, ontwikkeld door de RSZ. Via deze digitale dienst kan je automatisch nagaan of bij een (onder)aannemer een sociale of fiscale inhouding moet gebeuren, op basis van gegevens uit de databanken van RSZ, RSVZ en FOD Financiën.
Toegang is enkel mogelijk nadat een Billretainmentconventie is ondertekend, ook voor mandatarissen die raadplegingen eventueel in jouw naam uitvoeren.
Extra tip: document everything well in your contract!
Prevention is better than cure. Therefore, make sure you clear contractual agreements with your (sub)contractor. This way you protect yourself to the maximum against unexpected financial risks and avoid discussions afterwards.
Do you need support? Questions about this article?
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