Understand · Payroll glossary
What is a social secretariat?
Updated on
A social secretariat (payroll provider) is the company that calculates pay and files the social security and tax declarations on the employer’s behalf. In 2026: the 15th (withholding tax (bedrijfsvoorheffing / précompte professionnel): declared and paid by the 15th of the month after salaries are paid). In Dutch: sociaal secretariaat.
Definition of a social secretariat
Most employers entrust their payroll to an approved social secretariat: it draws up the payslips, calculates contributions and withholding tax, and prepares the declarations to the National Social Security Office (NSSO) and FPS Finance. The employer remains responsible for the amounts and payments.
That is why two correct payslips can look very different: each secretariat (SD Worx, Securex, Partena Professional, Acerta, Liantis…) has its own layout.
The key figure in 2026
Source: À quel moment calculer et verser le précompte professionnel : le 15 du mois qui suit, ou dans les 15 jours après le trimestre, Securex (secondary source). Value in force on 1 October 2026.
Worked example
October’s salary is paid on 30 October 2026: the social secretariat declares and pays the withholding tax by 15 November 2026 at the latest. The DmfA (quarterly social security declaration) for the fourth quarter is due by 31 January 2027, and the year’s tax form 281.10 (fiche 281.10) by 28 February 2027.
In Dutch: sociaal secretariaat
On a Dutch-language payslip (loonbrief), the social secretariat is called ‘sociaal secretariaat’; on a French-language one (fiche de paie), ‘secrétariat social’. Also called payroll provider in English.
Dutch term taken from: CSC/ACV (secondary source).
Not to be confused with…
- Social insurance fund: the body a self-employed person must join to pay their social security contributions and build up their rights.
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Related terms
- NSSOFrom gross to net · in Dutch: RSZ (Rijksdienst voor Sociale Zekerheid)
- Tax form 281.10Tax and tax return · in Dutch: loonfiche 281.10
- Withholding taxFrom gross to net · in Dutch: bedrijfsvoorheffing
Sources
Parameters in force on 1 October 2026. Each parameter links to its source, the official one where it exists; a secondary source is flagged as such.
- À quel moment calculer et verser le précompte professionnel : le 15 du mois qui suit, ou dans les 15 jours après le trimestre, Securex (secondary source).
- Formalités obligatoires à l’égard de l’ONSS : DmfA dans le mois qui suit le trimestre, cotisations au plus tard le dernier jour de ce mois, Securex (secondary source). Cross-checked with: UCM, NSSO provisional payments (reference amount of €4,000).
- Loonbrief onder de loep 2026 (Dutch-language payslip guide), CSC/ACV (secondary source).