Status & contributions
INASTI
Institut National d'Assurances Sociales pour Travailleurs Indépendants (National Institute for the Social Security of the Self-employed, NISSE)
By the Finances Indépendants editorial teamUpdated on 4 min readAlso known as: NISSE, INSS, RSVZ
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Contents
What is the NISSE?
The NISSE, INASTI in French and RSVZ in Dutch, is the public institute that manages the social security status of self-employed people in Belgium. It sets the contribution rules, keeps career records and pays out self-employed pensions.
You do not deal with it directly for your payments. Every self-employed person joins an approved social insurance fund of their choice, which collects the contributions, passes them on and charges management fees of between 3.05% and 4.25% depending on the fund.
How much NISSE contributions cost
Contributions are calculated on net taxable professional income, that is, after deducting business expenses and before tax. The scale decreases by band.
- 20.5% on the portion of income up to €75,024.54.
- 14.16% on the portion between €75,024.54 and €110,562.42.
- No contribution above €110,562.42: the ceiling is absolute.
The three-year lag and regularisation
This is the leading cause of cash-flow gaps for self-employed people, and the least understood. A year's contributions are calculated provisionally on income from three years earlier, the only income the authorities know for certain at that point.
The NISSE regularises provisional contributions 2 to 3 years after the income year, on the basis of the official tax return. Regularisation therefore comes around 2 years after the contribution year, and can result in an extra payment or a refund.
Two lags thus stack up, and a self-employed person whose business is slowing down pays on their best years. You can ask your fund to adjust your provisional contributions, with proof that your income has fallen.
The main categories of contributors
The amount due depends less on your profession than on the category the NISSE puts you in.
- Self-employed as a main occupation: minimum quarterly contribution of €890.42, due even with no income, on a minimum income of €17,374.08.
- Self-employed as a secondary occupation: No contribution is due as long as annual net income stays below €1,922.16. Above that, the contribution is calculated at the ordinary rates on the whole of the income, not just on the part above the threshold (voluntary contributions are possible below the threshold to build up entitlements).
- Assisting spouse (maxi-status): minimum income of €7,632.44, minimum quarterly contribution of €391.16 excluding management fees.
- Pensioner continuing a self-employed activity: No contribution is due below €3,844.32 of annual net income, for pensioners and for self-employed people who have reached the statutory age without drawing a retirement pension and have requested the "opt-out". Above that, a pensioner (retirement pension, early or at the statutory age) pays 14.7% on the whole of the income. Someone who has opted out with no pension at all pays 20.5% from €3,844.32 to €17,374.08, then the contributions of a self-employed person as a main occupation; someone who has opted out with only a survivor's pension pays 14.7% from €3,844.32.
What rights the contributions open up
NISSE contributions are not a tax: they fund entitlements. A self-employed statutory pension, health care, incapacity benefits, maternity leave, family allowances and the bridging right if you stop trading.
Being up to date with contributions is also a condition for deducting a PLCI/VAPZ (free supplementary pension for the self-employed) premium. A late payment can therefore cost you twice: in social security rights and in tax advantage.
Not to be confused with
The terms close to INASTI and what sets them apart.
- INASTI and NSSO
- The NSSO (ONSS/RSZ) manages social security for employees and employer contributions. The NISSE manages it for the self-employed. A company director falls under the NISSE, not the NSSO.
- INASTI and Social insurance fund
- The fund is your day-to-day contact: it calls in and collects contributions and charges management fees. The NISSE is the public institute that sets the rules and keeps your career record.
- INASTI and Personal income tax (IPP/PB)
- Social security contributions are calculated on net taxable income and are themselves deductible when calculating personal income tax. They are two separate charges, in that order.
Further reading
- Social security contributions
- Adjustment of contributions
- Social insurance fund
- Adjustment (regularisation) of social security contributions
- Assisting spouse
- ONSS, Office National de Sécurité Sociale (National Social Security Office, NSSO)
- Provisional exemption (social security contributions)
- All glossary terms
INASTI: frequently asked questions
20.5% of net professional income up to €75,024.54, then 14.16% up to €110,562.42. Above that, no further contribution is due. The fund's management fees come on top.
Provisionally on your income from three years earlier, the only income known for certain at that point. The NISSE then regularises around 2 years after the contribution year, on your actual income, and claims or refunds the difference.
€890.42 per quarter, calculated on a minimum income of €17,374.08. This contribution is due even if your actual income is lower, or nil.
No contribution is due as long as annual net income stays below €1,922.16. Above that, the contribution is calculated at the ordinary rates on the whole of the income, not just on the part above the threshold (voluntary contributions are possible below the threshold to build up entitlements). Above this threshold, the same rates as for a main occupation apply.
Yes, on a reasoned request to your fund, with proof that your income for the current year will be below certain legal thresholds. The reduction is provisional: the later regularisation will in any case be based on actual income, with surcharges if the reduction was not justified.
Official source
- NISSE. View (new tab)(Official source, accessed on 2026-10-13)