Employers have the option of providing their employees a seniority bonus free from income tax and social security contributions, be it maximum twice during their careers in the company concerned, which is:

- a first seniority bonus corresponding to maximum once the gross monthly pay, no earlier than during the calendar year in which the employee completes his or her 25th year with the employer’s company;
- a second seniority bonus corresponding to maximum twice the gross monthly pay, no earlier than during the calendar year in which the employee completes his or her 35th year with the employer’s company.

Recently, the Belgian national social security office (RSZ/ONSS) published in its instructions to employers that, if the permitted amount of the seniority bonus is exceeded, only the excess amount will be liable to social security contributions. The previous position was that, where too high a seniority bonus had been granted, the entire amount of the bonus would be liable to social security contributions.

According to the same RSZ/ONSS instructions, companies may also calculate the seniority bonus on the basis of the average gross monthly pay they pay to (their own) employees instead of the gross monthly pay earned by the employee concerned. Note, however, that companies are not allowed to apply both calculation modes during one and the same calendar year.

Finally, the RSZ/ONSS also allows seniority bonuses to be provided in the form of gifts in kind, cash gifts or gifts in the form of payment vouchers (‘betaalbons’/'bons de paiement’).

Now it remains to be seen whether the tax authorities will either adopt the position of the RSZ/ONSS or rather maintain the current rules on granting seniority bonuses.