Status & contributions
Social insurance fund
By the Finances Indépendants editorial teamUpdated on 3 min readAlso known as: Caisse d'assurances sociales, Sociaal verzekeringsfonds, Social security fund, National Auxiliary Fund, Changing fund
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Contents
What is a social insurance fund?
It is the state-approved body that manages your social security status as a self-employed person on your behalf. It registers you, calculates your quarterly contributions, collects and passes them on, then adjusts the amount once your actual income is known. It is your day-to-day point of contact, while the [NISSE](/fr/glossaire#inasti) sets the rules and keeps your career record.
Several private funds exist side by side, including Acerta, Group S, Liantis, Partena, Securex, Xerius and the UCM fund. Alongside them, the National Auxiliary Fund is the NISSE's public fund: it takes in those who choose it and those who have not chosen a fund in time.
What the fund does, and what it does not
The fund handles everything to do with your contributions: calculating them, calling them each quarter, their [adjustment](/fr/glossaire#regularisation-cotisations) and applications for a reduction or exemption, which go through it. It also receives applications for the [bridging right](/fr/blog/droit-passerelle-independant-conditions) in the event of a forced cessation.
It does not deal with everything. Incapacity for work is reported to your health insurance fund (mutuality), which pays the benefits. Tax is a matter for FPS Finance. The fund nonetheless remains essential to these rights: if your contributions are not in order, the health insurance fund may refuse to pay benefits.
- Membership and calculation of provisional contributions.
- Adjustment on actual income, with a top-up or a refund.
- Applications for a reduction, an exemption or a repayment plan.
- Applications for the bridging right.
When to join, and what happens if you forget
Before your activity starts, at the latest. The rule applies to the self-employed as a main occupation and as a secondary occupation alike. Registering with the Crossroads Bank for Enterprises (CBE) does not replace membership of a fund: these are two separate steps.
A self-employed person who has not joined in time receives a formal notice from the NISSE giving them 30 days to choose a fund. After that, they are automatically registered with the National Auxiliary Fund. The delay also exposes them to an administrative fine.
Choosing your fund, then switching
The choice is free and contributions are the same everywhere: the scale is set by law. What varies is the management fees, from 3.05% to 4.25% of contributions, and the service: accessibility, online tools, help with formalities.
Switching funds is regulated. The switch takes effect on 1 January, and the new fund handles the formalities. Several conditions must be met.
- Having been a member of your current fund for at least four years.
- No longer owing it anything.
- Not having reached your pension year: switching is ruled out from 1 January of the year in which you reach pension age or take an early pension.
- For an assisting spouse: staying with their partner's fund, unless both switch together.
Not to be confused with
The terms close to Social insurance fund and what sets them apart.
- Social insurance fund and the NISSE
- The NISSE is the public institute that sets the rules of the social security status and keeps the career records of the self-employed. The fund is the approved body, chosen by the self-employed person, that calls and collects contributions.
- Social insurance fund and the health insurance fund (mutuality)
- The health insurance fund reimburses healthcare and pays incapacity for work benefits. The social insurance fund collects the contributions that open these rights, but does not pay them out.
- Social insurance fund and the business one-stop shop
- The business one-stop shop registers the business with the Crossroads Bank for Enterprises. Joining a social insurance fund is a separate step, which must also be completed before you start.
Further reading
- INASTI
- Adjustment of contributions
- Social security contributions
- Contributions simulator
- Adjustment (regularisation) of social security contributions
- Assisting spouse
- INASTI, Institut National d'Assurances Sociales pour Travailleurs Indépendants (National Institute for the Social Security of the Self-employed, NISSE)
- ONSS, Office National de Sécurité Sociale (National Social Security Office, NSSO)
- All glossary terms
Social insurance fund: frequently asked questions
No. The contribution scale is set by law and is identical in every fund: 20.5% of income up to €75,024.54 for someone self-employed as a main occupation. Only the management fees differ, from 3.05% to 4.25% of contributions, along with the quality of service.
It is the public social insurance fund, run by the NISSE. You can choose it like any other fund. It also automatically takes in self-employed people and companies that have not chosen a fund within the deadline set after a formal notice.
No. Incapacity for work is reported to your health insurance fund, which recognises the incapacity and pays the benefits. The social insurance fund comes in earlier: having paid your contributions, or being exempt from them, is one of the conditions for receiving these benefits. A contribution debt can therefore block a right.
Yes. Compare the management fees, the contact channels and the online tools, then join directly. This information is provided for guidance only and does not constitute personalised advice. Consult a licensed professional before making any decision.
Official source
- NISSE, Joining a social insurance fund. View (new tab)(Official source, accessed on 2026-10-13)