Self-employed persons exercising a main activity


Self-employed persons are those who exercise a remunerative professional activity for which they are not contractually bound to an employer, making them their own bosses to a certain extent.

Self-employed persons are also treated as such for social security purposes. Consequently, unlike public or private sector employees, if you are self-employed you must join a social insurance fund and pay social security contributions.

As a self-employed person you may exercise either a main activity or a complementary activity (if your main activity is as a salaried employee).

Natural and legal persons

Two types of person may count as self-employed:

  • natural persons: there is no clear separation between your private belongings and the property owned by your company. Consequently, you pledge all you own, including personal assets, to cover your business risk;
  • or legal persons: by setting up a legally incorporated company. From the legal viewpoint, such a company is totally independent in terms of its rights and obligations and its assets are clearly distinct from those of its associates.

In this context we will only consider natural persons. For more information on legal persons, see the sections of the website devoted to companies.

Types of independent activity

Self-employed natural persons can exercise a professional activity in a number of domains, including:

  • tradesmen (including itinerant traders: door-to-door salesmen, hawkers or market stallholders);
  • persons exercising liberal professions (architects, doctors, lawyers, etc.);
  • farmers and livestock breeders;
  • company representatives.

Criteria to fulfil before exercising a profession on a self-employed basis

  • You must normally be a major (over 18 years old), but for practising craftsmen the minimum age is 16, provided that you have authorisation from your parents or tutor.


Some categories of person may not - or may no longer - exercise commercial activities on a self-employed basis. These categories include:

  • persons who have been declared bankrupt; 
  • persons sentenced for fraudulent bankruptcy;
  • persons declared legally ineligible for such an activity (following a criminal sentence against them);
  • persons on probation.

Steps to be taken

  • choose how you plan to exercise your activity: either as a natural person or as a company;
  • open a bank account;
  • register with the guichet d'entreprises/ondernemingsloket (one-stop- shop for businesses) and check your entrepreneurial aptitude and management skills;
  • register with the Central Enterprise Databank (BCE/KBO)External link and obtain an enterprise number and an establishment number;
  • join a social insurance fund and pay social security contributions;
  • obtain a licence (if required for your profession).

Affiliation to a social insurance fund

As a self-employed person, you must join a social insurance fund, doing so:

  • either 6 months before starting your activity;
  • or within 90 days after starting your activity.

If you fail to register with such a fund within 90 days, the National Institute for the Social Security of the Self-employed  (NISSEExternal link)External linkwill ask you to put your affairs in order. Should you fail to meet this formal requirement, you will be affiliated to the National Fund (Caisse nationale auxiliaire/Nationale Hulpkas).

If you set up a company, it too must join a social insurance fund for self-employed persons (even if you yourself are already affiliated in a personal capacity) and will have to pay an annual fee related to its status as an independent concern. When joining, non-Belgian nationals will have to submit any authorisations required for them to exercise their independent activity in Belgium, namely:

  • either a professional card (carte professionnelle/beroepskaart) for foreign workers wishing to work in Belgium on a self-employed basis;
  • or the necessary documents relating to their residency for some nationals from Central and Eastern Europe wishing to exercise a non-salaried activity or set up a company in Belgium.

How your social security contributions are calculated

How are your social security contributions calculated?

Your social insurance fund takes your reference income as its basis when calculating your social security contributions:

  • net professional income during the year taken as a reference: the contributions you have to pay represent a percentage of your professional income.
    The income serving as the basis for calculating your contributions comprises your combined net revenue as a self-employed person or assistant during the third calendar year (the so-called reference year) prior to the year in which your contributions are due;
    Example: Your 2004 contributions are calculated on the basis of your 2001 revenues. Minimum and maximum amounts also apply.
  • your re-evaluated net professional income;
  • you will also have to pay a sum to cover administrative costs of your social insurance fund.