Knowledge base

Practical guides on the Belgian withholding obligation.

nsso·9/22/2026·7 min read

Declaration of works to the NSSO: when, how and why

Anyone having immovable works carried out in Belgium must declare them to the NSSO beforehand. Here is who declares, within what deadline, through which channel and what happens if you forget.

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nsso·9/1/2026·7 min read

How to find your supplier's NSSO number: a guide for clients

Finding your supplier's NSSO number is the first step of every withholding obligation check. Here are the four most reliable ways, plus the pitfalls to avoid.

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guides·6/11/2026·9 min read

Belgian withholding obligation for contractors: complete 2026 guide

Everything about the Belgian withholding obligation in 2026: when to check, how much to withhold, who to pay and how to avoid penalties.

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