Declaring employees in Belgium
To enable a correct follow-up by the Belgian social security, an employer must submit two types of declaration for his employees. The first one is the immediate declaration (Dimona), and the second one is a quarterly reporting of executed work and salaries (DmfA).
You are required to declare every new person you take on and every person leaving your employment to the NSSO. It is important that you submit this declaration correctly and on time: before an employee starts working for you, a Dimona must be in place for them.
Dimona is used for any type of employment contract.
What do you need to declare?
You will need to fill in the following basic information in Dimona:
- the employee’s national registration number or, if this is not available, their identification details,
- additional information about the employee: Joint Committee and employee type,
- the period for which the employee will be working: start date and end date (if known). For occasional staff: likewise the start and end date.
Explanations of terms such as Joint Committee (Paritair Comité) and the types of employees can be found on the page on what information to provide on the Administrative instructions part of the social security portal (in French).
As an employer, you must declare the work done by and salaries paid to your employees every quarter in the multifunctional declaration DmfA. The information from the DmfA is sent to various Belgian social security institutions.
What is the DmfA for?
The DmfA’s main functions are:
- to determine the amount of social security contributions employers and employees need to pay
- to submit to the government in a one-off communication the salary and work information of all employees
The Belgian social security system applies to:
- employees who work on Belgian territory and whose employer is based in Belgium
- employees who are attached to the Belgian registered office of a foreign company
These employees have to be declared in Dimona and DmfA, just as Belgian employees are.
The only exceptions are residents of countries with which Belgium has concluded an international treaty or a bilateral agreement stipulating that the Belgian system does not apply. A list of these countries can be found on the page Agreements of the website Coming2Belgium.
The Dimona and, in particular, the DmfA are closely linked to Belgian employment and social security legislation. Given the critical importance of filling them in correctly, the social security institutions provide comprehensive legal information. This information is regularly updated. It can be found on the Administrative instructions part of the social security portal (in French).
The declarations are outsourced by many employers to a social secretariat (accredited by the Minister of Social Affairs) or a payroll services firm. An accredited social secretariat is empowered to collect your social security contributions, while a payroll services firm is not.
To mandate a third party to submit declarations for you, use the secure online service Mahis (in French) on the Belgian social security portal.
Social Security Contact Centre
- Telephone: +32 (0)2 511 51 51
- Contact form for the social security portal - compan (in French)