INASTI social security contributions: the practical guide

What's inside

INASTI social security contributions are the biggest source of confusion for the self-employed in Belgium, especially the adjustment three years later. This guide explains how it works in plain terms, with worked examples for the self-employed as a main occupation, as a secondary occupation and for assisting spouses.

Who is this guide for?

The guide is designed for the following profiles. If you recognise yourself in at least one of them, reading it will save you hours of searching through scattered sources.

• New self-employed people (the first 3 years are decisive)
• Self-employed people with rising income (anticipating the adjustment)
• Self-employed people with falling income (applying for a reduction)

Detailed PDF contents

These are the chapters covered. Each chapter starts with a direct answer to the main question, followed by the reasoning and the legal references.

1. INASTI status: main occupation, secondary occupation, assisting spouse
2. 2026 scale: 20.5% up to €75,024.54 / 14.16% up to €110,562.42
3. Provisional contributions vs adjustment after 3 years
4. Possible exemptions and deferrals
5. Optimising your calculation base (PLCI, business expenses)
6. Social insurance funds: Acerta, Liantis, Partena, Securex, Xerius

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