Checkinatwork explained: reporting presences on a Belgian site
On larger Belgian sites every presence must be reported to the NSSO each day. Here is when Checkinatwork applies, who reports, how it works and what inspectors find.
Checkinatwork is the daily presence registration on Belgian immovable works sites. Anyone working on the site must be reported to the NSSO, per day and per person. The duty exists alongside the declaration of works and the withholding obligation.
When the duty applies
Presence registration applies to sites where the total amount of the immovable works reaches the legal threshold. Above that threshold, every contractor and subcontractor must register the presence of their workers and self employed people daily. Below the threshold the duty does not apply, but the declaration of works may still be mandatory.
Who reports whom
| Situation | Who registers |
|---|---|
| Worker of a contractor | the employer, or the worker through the mobile app |
| Self employed subcontractor | the self employed person |
| Temporary agency worker | the agency, in agreement with the user company |
| Foreign worker | the employer, after a Limosa declaration |
How to register
There are four channels: the web application on the social security portal, the mobile app, a badge reader on site, and a direct connection from your own software. You need the site number from the declaration of works and the identification number of the person involved. Registration happens on the day itself, before work starts.
What inspectors find
The most common findings are: people present who are not registered, registrations completed after the fact, and a site number that does not match the declaration of works. A missing registration leads to an administrative fine per unregistered person and strengthens a finding of joint liability for social security debts.
How this relates to your other duties
Three duties meet on the same site:
- Declaration of works, before the start, with all subcontractors.
- Checkinatwork, daily, per person present.
- Withholding obligation, at every payment, per contractor or subcontractor.
The first two are about who works. The third is about money: if your contractor has social security or tax debts, you must transfer part of the invoice to the authorities instead of paying it out. That status changes constantly, so a check from last month proves nothing today.
Practical tips
- Keep the site number centrally, so whoever registers does not have to look it up.
- Get written confirmation that subcontractors handle their own registrations.
- Check weekly that registrations match the planning on site.
- Follow each contractor's debt status automatically, instead of checking by hand at every payment.
Frequently asked questions
Does a supplier who only delivers materials need registering? No, the duty covers people carrying out immovable works.
Can a worker register themselves? Yes, through the mobile app, but responsibility stays with the employer.
Does Checkinatwork replace the withholding obligation check? No. They are two separate duties with different sanctions.
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.
Requesting an NSSO certificate: who, where and how long it is valid
Step by step: which document you need for a withholding obligation check, where to request it and how long it stays valid.
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.