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Secondment and parallel activities

last modified May 14, 2014 10:34 AM
Belgian social security authorities take new position regarding the impact of parallel activities on the application of the secondment rule


Regulation 883/2004 is the main instrument dealing with the coordination of social security systems within the European Economic Area. One of the most important chapters concerns the determination of the applicable social security legislation in cases with a cross-border element, e.g. the temporary secondment of employees.

Further to discussions at European level, the Belgian social security authorities (RSZ/ONSS) have adopted a new position regarding the impact of parallel activities on the application of the secondment rule.

The new position of the RSZ/ONSS

The secondment rule guarantees that an employee remains covered by his home country’s social security system during a temporary assignment abroad (max. 2 years, extendable up to 5 years). Until now, it was unclear whether the performance of parallel activities could have an impact on the secondment rule’s applicability.

The RSZ/ONSS has now taken the position that a secondment cannot be combined with parallel activities. In case of such parallel activities, the secondment rule becomes inapplicable and the individual’s situation has to be assessed according to:

  • The work state rule, in case of parallel activities in the Host State
  • The simultaneous employment rules, in case of activities in the Home State or any other state

Clarifying examples

Our assessment

A secondment cannot be combined with a parallel professional activity, neither in the Host State nor in any other state. This position has officially been adopted by the European Administrative Commission on the coordination of national social security schemes.

However, upon first analysis, this position does not seem to have any impact on:

  • “Parallel activities” that can be considered as “marginal activities” (<5% of total working time and/or remuneration);
  • Secondments under most bilateral social security agreements between Belgium and non-EEA countries and a parallel activity in the Host State (1).

It should be noted that the RSZ/ONSS does not provide a definition of “parallel activities” in its new position paper. It can be presumed that it should concern a permanent and structural activity, as opposed to a one-off, ad hoc or temporary activity. Next to this, a non-remunerated parallel activity will probably meet the definition of “marginal activities” if less than 5% of the total working time is dedicated to it. However, further clarification on the “parallel activities” notion seems to be indispensable for daily practice.

In any case, this position will clearly have a significant impact on the employer’s possibility to second employees from and to Belgium. Consequently, complex employment structures will have to be revisited in view of their compliance with this new position regarding the applicable social security legislation. Moreover, employers will have to keep track of any additional professional activities of their employees (e.g. director mandates), considering the possible impact on their social security situation.

Filip Van Overmeiren, Advocaat/Avocat, Tel.: +32 2 800 71 17, E-mail:   

(1) However, it should be noted that for secondees under a bilateral treaty, a parallel activity in a EEA country other than the Host State can lead to the application of the simultaneous employment rules of Regulation 883/2004.


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