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    If, as an entrepreneur, you wish to hire staff, you will have to complete a series of administrative formalities imposed by social and tax legislation.

    Steps to take at the NSSO

    If you are hiring one or several workers for the first time, you must:

    • identify yourself as an employer with the NSSO
    • make an immediate employment declaration (DIMONA)
    • make a quarterly multifunctional declaration

    Identifying Yourself as an Employer with the NSSO

    Identification with the National Social Security Office (NSSO) can be done via the Wide online service accessible on the portal site of the Social Security.

    Submitting a “DIMONA” declaration

    When you hire staff, you must submit an immediate employment declaration (DIMONA) to the NSSO.

    This process, which is mandatory for all employers in all business sectors, can only be done electronically.

    With this declaration you inform the NSSO that you have employed someone within the company.

    Each employee is assigned a personalised DIMONA code which allows the social security bodies to immediately access the information relating to the identity and the employer-employee relationship and any related changes (for example, if an employee leaves). As such, the information is provided only once.

    Wide is directly integrated into the DIMONA online service. Any new employer can therefore declare their first employee when identifying themselves to the NSSO.

    Submitting a quarterly multifunctional declaration

    In addition, you have to submit a quarterly multifunctional declaration to the NSSO, which specifies the work and remuneration of all your employees.

    How much do these steps cost?

    These formalities are free of charge if you complete them yourself.

    A fee is charged, if an enterprise counter or a social secretariat is involved. Other intermediaries can also assist you in these steps, for a fee (specialised offices, employers' organisations, etc.).

    More Information?

    All useful information and forms are available on the portal site of the social security. The NSSO website “” also offers a concrete overview of all the information you need as a future employer.

    National Social Security Office (NSSO)
    Place Victor Horta 11
    1060 Brussels
    Tel.: +32 2 509 59 59
    NSSO Website -
    Instructions administratives

    Affiliation to an Accredited Social Secretariat

    Social secretariats are bodies recognised and controlled by the public authorities. In particular, they act as the employer's representative with the NSSO.

    Affiliation to a social secretariat is not mandatory. You may decide to solicit them to carry out the formalities prescribed by the social legislation concerning the hiring and management of staff on your behalf. Business counters often have a related social secretariat towards who they will redirect you.

    Affiliation to a social secretariat is a paying service. You are strongly encouraged to ask for an estimate of their services before using them.

    The list of accredited social secretariats is available on the website of the Union of Social Secretariats.

    Cost of affiliation to an accredited social secretariat

    As a new employer, you can benefit, under certain circumstances, from a contribution of the NSSO to the costs resulting from your affiliation to an accredited social secretariat. This contribution may be granted to you :

    • when you hire your first worker (and up to a maximum of six workers)
    • provided that you have received the reduction in employer's social security contributions for “first employment” when hiring this worker.

    Other Administrative Formalities

    In addition to the steps with the NSSO and the possible affiliation to an accredited social secretariat, you will also have to fulfil various other obligations:

    • affiliation to a family allowance fund;
    • subscribing to an insurance which covers accidents at work;
    • compliance with legislation on well-being at work;
    • compliance with the conditions of employment of workers, etc.

    Withholding tax

    Any business owner (self-employed or company) who wishes to hire staff must meet various tax obligations.

    A self-employed person or a company that pays or grants remuneration, including benefits of any kind (provision of a car, a computer, a mobile phone, a home, etc.) to its employees or workers must deduct withholding tax. You are entitled to deduct this withholding tax from the taxable income you pay or allocate.

    If you bear the withholding tax that is due yourself instead of deducting it, this constitutes a benefit in kind that is taxable on the part of your employees.

    The withholding tax is calculated on taxable remuneration after deduction of personal social security contributions.

    You must file the withholding tax declaration, by electronic means, within 15 days of the end of the month or quarter in which you paid or allocated the remuneration.

    The withholding tax due must also be paid in full within the same period, unless an exemption from payment can be applied to you. In the latter case, you are fully or partially exempt from paying the withholding tax that is due to the Treasury.

    There are various exemptions from paying withholding tax. These apply to the following:

    • additional work carried out;
    • researchers;
    • shift work and night work;
    • shift work and real estate work;
    • wage adjustment (AIP);
    • start-up companies;
    • young employees;
    • employee training;

    The conditions and rules for exemption vary for each of these cases.

    In order to corroborate the declarations made, you must electronically file tax slips on behalf of each income recipient before 1 March of the year following the year to which the slips relate.

    You will find more information about the withholding tax on professional income in the "Personnel and remuneration" section on the website of the FPS Finance.

    Last update
    13 November 2023