Calculation and payment of social security contributions

In Belgium, social security contributions are collected by the National Social Security Office (NSSO). Here is an overview of how they are calculated and when they have to be paid.

The National Social Security Office (NSSO) collects all social security contributions for employees. These include employers' and personal basic contributions as well as most contributions for the Funds for livelihood security and contributions to the Funds for Closure of Enterprises, contributions for double holiday allowance, etc.

The NSSO calculates what contributions you have to pay. You or your social secretariat monthly receive a document with the full calculation of the advance payment. Every quarter you have to pay the difference between the monthly advance payment and the total quarterly amount on the basis of your quarterly DmfA declaration. Consult the DmfA brochure for more information on how to make a DmfA declaration. You also find information on DmfA on the Social security enterprise portal (in French).

Payment deadlines

The monthly advances must be paid at the beginning of the subsequent month.

Payment of the difference between the total of advance payments and the total amount based on the quarterly DmfA declaration must be received by the NSSO at the latest on the last day of the month following the quarter for which the declaration was submitted.

Check the exact payment deadlines on the Social security enterprise portal calendar (in French).

Payment details

The amount due based on your quarterly DmfA declaration should be deposited on IBAN BE63 6790 2618 1108 (BIC PCHQBEBB). When paying, always use the structured communication with the format +++NNN/NNNN/NNNNN+++.

You receive the structured communication either via bpost (Belgian postal service) or in your e-Box Enterprise mailbox, in a document entitled 'Communication structurée du paiement du solde trimestriel', which means ‘Structured communication of the quarterly balance payment'.

Payment confirmation

Your bank statement is valid as proof of payment.

Use the online service Consultation invoices employers to check all NSSO invoices for your company. It is available for employers and social secretariats or payroll service firms mandated by the employer. Check the Consultation invoices employers manual for information on how to use this online service. You also find information on Consultation invoices employers on the Social security enterprise portal (in French).

National Social Security Office (NSSO)

You can also get in touch via our Contact page.