Belgian Social Contributions Guide for Self-Employed

Published: · 8 min read · By Taxmo

Quick Answer

Belgian sociale bijdragen for self-employed are calculated on your professional income from three years ago (the reference year): 20.50% on income up to EUR 75,024.54 (2026), 14.16% on the portion from EUR 75,024.54 to EUR 110,562.42, and 0% above that cap. Because the bill lags reality, your fund issues a regularisation about two years after the income year: you pay the difference if you earned more or get a refund if you earned less. Voluntary quarterly top-ups avoid the back-bill after a good year. Paid contributions are 100% deductible as a business expense for personenbelasting. All funds (Acerta, Liantis, Securex, Partena, Xerius, UCM) apply the same legal percentages.

  • Rate 2026: 20.50% on income up to EUR 75,024.54.
  • Rate above: 14.16% from EUR 75,024.54 to EUR 110,562.42, then 0% (capped).
  • Basis: professional income from 3 years ago (reference year).
  • Regularisation: about 2 years after the income year; voluntary top-ups possible any quarter.
  • Deductibility: 100% deductible for personenbelasting.

Sociale bijdragen are Belgium's social-security contributions for self-employed professionals, replacing the employer-employee RSZ for salaried workers. They fund your pension, healthcare, family allowance, and replacement income.

How the contribution is calculated

The contribution is a percentage of your professional income from three years ago (the reference year). The percentages are progressive:

Because the bill is based on income from 3 years ago, your contribution lags reality. After the official income arrives (~2 years after the year), the fund issues a regularisation: pay the difference if you earned more, or get a refund if you earned less.

The regularisatie surprise

Growing self-employed often face a large back-bill 2-3 years after a good year. To avoid this you can pay voluntary top-ups any quarter via your fund. Our social contributions planner calculates the optimal top-up from your live bookkeeping.

Funds you can affiliate with

Acerta, Liantis, Securex, Partena Professional, Xerius, UCM, plus the residual fund Caisse auxiliaire des indépendants. All apply the same legal percentages; service quality and online tools differ.

Tax deductibility

Paid sociale bijdragen are 100% deductible as a business expense for personenbelasting. The deduction reduces your taxable professional income before the income tax brackets apply.