Summary
The Supreme Court has issued an important ruling on the social security treatment of Restricted Stock Units (RSUs) granted by a foreign parent company to employees working for a Belgian subsidiary.
In its judgment of 29 June 2026 (Nr. S.24.0021.N), the Court ruled that benefits granted to retain employees, encourage their continued commitment or ensure that they continue to perform their duties diligently can constitute remuneration for work.
The judgment significantly limits the possibility of keeping foreign RSU awards outside the Belgian social security system merely because the Belgian employer does not grant or finance the shares.
RSUs in an international employment context
Restricted Stock Units are frequently used by multinationals as part of their employee incentive programs.
Under a typical RSU plan, an employee receives a conditional right to shares in the company. The shares are delivered at a later date, usually once certain vesting conditions have been satisfied. These conditions commonly require the employee to remain employed for a specified period and may also include individual or corporate performance conditions.
For employees working in Belgium, RSUs are often granted directly by a foreign parent company rather than by their Belgian legal employer.
This distinction has historically created an important question for Belgian social security purposes: can an advantage granted and financed by a foreign group company nevertheless constitute remuneration subject to Belgian social security contributions?
Definition of remuneration
Belgian social security contributions are generally calculated on an employee’s remuneration.
For this purpose, the social security legislation refers to the concept of ‘remuneration’ contained in the Belgian Wage Protection Act of 12 April 1965.
An important distinction must be made between two categories of benefits.
First, a benefit that constitutes consideration for work performed under the employment contract is remuneration by its very nature.
Second, other benefits may qualify as remuneration when the employee is entitled to them as a result of the employment relationship and they are borne by the employer.
This distinction became particularly important for international equity plans because foreign RSUs are frequently granted and financially borne entirely by a foreign parent company.
Court of Cassation standpoint
This is not the first time the Belgian Supreme Court has considered this issue.
In its judgment of 5 September 2022 (Nr. S.21.0007.N), the Court rejected the proposition that RSUs granted by a foreign parent company could automatically be treated as remuneration subject to Belgian social security contributions.
That judgment left considerable room for discussion where the Belgian employer neither granted nor financed the RSUs.
If the benefit was not granted as consideration for work and was not directly or indirectly borne by the Belgian employer, there was an argument that it fell outside the Belgian social security remuneration concept.
For international groups, this distinction was particularly relevant because many global equity plans are administered entirely at parent-company level abroad.
Relevant facts
Following this earlier Supreme Court judgment, the dispute then continued before the Antwerp Labour Court of Appeal.
The RSUs concerned were granted by the foreign parent company to selected employees within the international group.
Importantly, the Belgian companies were involved in the selection process: they could suggest employees to the parent company and provide reasons supporting their recommendation. The purpose of the RSU program was also relevant. The shares were intended, among other things, to bind selected employees to the company over a longer period.
The Antwerp Labour Court of Appeal nevertheless concluded that the RSUs did not constitute consideration for work performed under the employment contract.
The National Social Security Office (NSSO/RSZ) challenged that conclusion before the Supreme Court.
Retaining employees can constitute remuneration for work
The Supreme Court rejected the reasoning adopted by the Labour Court of Appeal. The key principle formulated by the Court is particularly important.
Benefits granted to retain employees, encourage them to continue their efforts or perform their duties diligently are connected with the employee’s work and can therefore constitute consideration for that work.
In other words, the fact that an RSU program is described as a retention program rather than as a reward for past performance does not remove it from the concept of remuneration. This is a significant clarification.
An employer can therefore no longer simply argue that RSUs are not remuneration because they are intended to keep an employee within the organisation rather than reward work that has already been performed.
What about RSUs granted entirely by the foreign parent company?
This is where the recent judgment becomes relevant for multinational employers.
Where an advantage constitutes consideration for work, it is not necessary to establish separately that the Belgian employer itself financed the benefit.
Consequently, the fact that the:
- RSUs are legally granted by a foreign parent company
- shares are financed by that foreign company
- Belgian employer does not reimburse the cost
- international RSU plan is administered outside Belgium or
- award is described as a retention incentive,
does not in itself prevent the RSUs from qualifying as remuneration for Belgian social security purposes. The economic and factual connection between the RSU award and the employee’s work becomes decisive.
Are all RSUs automatically subject to Belgian social security?
Not necessarily.
The judgment should not be read as establishing that every RSU granted to a Belgian employee automatically constitutes remuneration.
The precise conditions of the plan remain relevant.
What the Court has made considerably more difficult, however, is the argument that an RSU falls outside the remuneration concept simply because it is granted for retention purposes or because the foreign parent company, rather than the Belgian employer, grants and finances the award.
The wording of the plan, vesting conditions, selection procedure, involvement of the Belgian employer and relationship between the award and continued employment should therefore all be properly examined.
In most conventional employee RSU programs, where vesting depends upon continued employment and the purpose of the award is to incentivize or retain the employee, the risk that the RSUs will be regarded as remuneration subject to Belgian social security contributions has become substantially higher.
When are Belgian social security contributions due?
RSUs are generally taxable when the employee obtains the shares, which will normally coincide with vesting. The taxable benefit is normally determined on the basis of the market value of the shares at that moment.
Where the employee is subject to the Belgian social security system and the RSUs qualify as remuneration, Belgian employee and employer social security contributions will in principle also become due on the relevant benefit. This can substantially increase the total cost of an international equity program for employees working in Belgium.
Existing RSU plans should be reviewed
The judgment is relevant for international groups that have historically excluded foreign-parent RSUs from Belgian social security on the basis that the Belgian subsidiary did not bear the cost of the plan. Those arrangements should now be reviewed.
Depending on the circumstances, the Belgian authorities may seek social security contributions for previous awards that were not included in the Belgian social security basis, subject to the applicable limitation periods and regularization rules.
Employers should therefore verify not only how future RSU vestings will be processed through payroll, but also whether the treatment adopted for previous vestings remains defensible following the new judgment.
Relevance beyond RSUs
The importance of the Court’s reasoning is not necessarily limited to RSUs.
Other benefits granted by a foreign parent company or another third party may face similar scrutiny if they are intended to reward, motivate or retain employees working for a Belgian employer. This could include certain retention bonuses, loyalty awards, share awards, performance incentives and other forms of group-based remuneration.
Particular attention should be paid to the vesting conditions, continued-employment requirements, selection process, involvement of the Belgian entity and the stated purpose of the incentive plan.
The legal structure through which the advantage is provided is therefore becoming less decisive than the underlying relationship between the benefit and the employee’s work.
For employees, the judgment is equally relevant. RSUs granted by a foreign parent company are generally already taxable as Belgian professional income where they relate to Belgian employment. The new judgment further reinforces the social security consequences that may accompany such awards.