Withholding obligation extended to social security debts of self-employed individuals

What is changing under the withholding obligation?

For certain types of work, clients and contractors must check whether their contractor or subcontractor has outstanding tax or social security debts. If a withholding obligation applies, they must pay part of the amount due directly to the relevant government authority. Only the remaining balance is paid to the contractor.

This system already applies to tax debts and social security debts owed to the National Social Security Office (NSSO). From 30 October 2026, it will also cover debts under the social security scheme for self-employed individuals.

For this new category, the withholding rate is 15% of the amount payable, excluding VAT. This amount must be transferred to the National Institute for the Social Security of the Self-Employed (NISSE).

Since 1 October 2026, NISSE has been sending information letters to businesses that may be affected. This gives them an opportunity to settle their outstanding debts before withholding measures are applied to their invoices.

Which types of work are subject to the withholding obligation?

The new NISSE withholding obligation applies to construction and other immovable property-related works that fall within the scope of the legislation. These include:

• construction and renovation work;

• repair work;

• maintenance work;

• certain cleaning activities;

carried out on immovable property.

Examples include electrical work in an office, painting commercial premises or cleaning a business building. The nature of the work being carried out is the determining factor.

Your company's own business activities are not decisive. In other words, you do not need to operate in the construction or cleaning sector to be subject to the withholding obligation. Retail businesses, consultancy firms and liberal professionals that commission such work may also be required to withhold part of the payment.

The obligation applies both to clients paying their contractors and to contractors paying their subcontractors.

An exception applies to individuals who have work carried out exclusively for private purposes.

Which social security debts are covered?

The extension of the withholding obligation covers, among other things:

• outstanding social security contributions owed by self-employed individuals that have become due;

• surcharges on those contributions;

• certain administrative fines;

• the annual company contribution.

Amounts for which a contractor is already jointly and severally liable may also be taken into account. This may be the case, for example, where a company is liable for the social security contributions of its partners or directors.

Not every outstanding debt automatically triggers a withholding obligation. For 2026, the annually indexed debt threshold is €2,647. Debts that do not exceed this threshold do not trigger the new withholding obligation.

Amounts that are not yet due or are covered by a payment plan that is being complied with are also excluded from the calculation.

Important: This threshold relates to the contractor's social security debts, not the value of your invoice. Withholding may therefore be required even for relatively small invoices.

How can you check whether withholding is required?

You can use Check Inhoudingsplicht to determine whether withholding is required by entering your contractor's company registration number.

Always check both the social security and tax sections.

The online tool displays a separate status for each section:

• Green: No withholding required.

• Red: Withholding required at the indicated percentage.

• Grey: The company falls outside the scope of the relevant withholding scheme.

Green and grey statuses include a validity date. A red status reflects the situation at the time of the check and may change if the company's debt situation changes.

If you receive a technical error message, repeat the check before paying the invoice.

It is advisable to carry out an initial check when entering into the contract. You should also check again before every payment. The contractor's status at the time of payment determines whether withholding is required. This also applies to advance payments and instalments.

How much do you need to withhold?

The new NISSE withholding requirement is added to the existing withholding obligations for NSSO and tax debts. Depending on the types of outstanding debt, the following rates apply:

The percentages are calculated on the amount payable, excluding VAT. Always follow the results and payment instructions provided by Check Inhoudingsplicht (= Check withholding obligation).

The total withholding is capped at 50%. If you are required to withhold 35% for NSSO debts and 15% for tax debts, no additional NISSE withholding applies. However, the underlying NISSE debt remains payable.

How do you transfer the withheld amount?

For social security withholdings, you can prepare the transfer through the online tool, which provides the payment details and a structured payment reference. For tax withholdings, you must follow the separate procedure established by the Belgian Federal Public Service Finance.

You deduct the required amount when paying the invoice and then transfer it in accordance with the instructions provided by the tool. Simply retaining the amount in your own bank account is not sufficient.

Make sure you also keep the following documents for your records:

• the consultation reference or result of your check;

• any relevant certificates;

• proof of payment.

This will allow you to demonstrate how the invoice was processed if questions arise later.

What happens if you fail to comply with the withholding obligation?

Failure to comply with the new obligation to transfer withheld amounts may result in an administrative fine equal to the amount that should have been transferred. For 2026, the indexed maximum fine is €10,578.23.

If another infringement occurs within one year of notification of a previous fine decision, a fine equal to twice the required withholding may be imposed, without this maximum limit.

An imposed fine may also be taken into account when determining whether your own company should become subject to the withholding obligation.

Are you a contractor or subcontractor yourself?

If so, it is important to check your own status regularly and monitor notifications in your e-Box. After all, amounts withheld from invoices you issue to clients have a direct impact on your available cash flow.

Have you received a warning, or does your company have a red status due to debts under the self-employed social security scheme? Contact your social insurance fund. It is your first point of contact for information about outstanding amounts and the options available to regularise your situation.

Remember to allow for processing times. Making a payment does not necessarily mean your online status will be updated immediately.

Make withholding checks a standard part of your payment process

From 30 October 2026, correctly checking withholding obligations will become even more important. A clear internal payment procedure can help your business avoid mistakes and potential fines.

Make sure you clearly assign responsibility for:

• checking whether the withholding obligation applies;

• reviewing the relevant invoices before each payment;

• transferring any amounts that must be withheld;

• keeping check results, certificates and proof of payment on file.

This makes withholding checks a routine part of your payment process rather than an additional check carried out afterwards.

Not sure whether certain activities fall within the scope of the rules? Or would you like advice on how to manage withholding obligations effectively within your business? Your trusted contact at Vandelanotte will be happy to help you develop the right approach.