Threshold & scope
When is Checkinatwork mandatory?
The short answer: on a construction site with a total value of €500,000 or more excl. VAT, the attendance of everyone working there must be registered through Checkinatwork, the attendance system of the NSSO (RSZ/ONSS). Below are the nuances that make the difference in practice: how to calculate the threshold, what if you only cross it during the works, and which works are excluded.
The threshold: €500,000 excl. VAT
Site started after 29 February 2016
Registration is mandatory from a total site value of €500,000 (excl. VAT).
Site started between 1 April 2014 and 29 February 2016
Back then the threshold was still €800,000 (excl. VAT). Relevant for long-running sites.
The most common mistake
The threshold refers to the total value of the site, not to your contract. If you do €20,000 of roofing work as a subcontractor on a €900,000 project, you must register your people just the same. Anyone who reasons “my share is too small” is wrong — and risks a fine per person.
Second pitfall: the threshold can be reached during the works, through additional work or an extension. From that moment on, registration is required, even if it wasn't at the start.
How do you know it applies to your site?
The contractor who declares the works receives a letter from the NSSO stating that attendance must be registered on that site. They are required to pass this on to everyone on the site — in practice often with a poster with a QR code at the site entrance. If there's a poster like that, it applies to your crew as well.
The site number you register with comes from the declaration of works. No declaration of works means no site to register on.
Which works and sectors are covered?
Works on immovable property
The classic construction site: new builds, renovation, demolition, roadworks, building services. Threshold: €500,000 excl. VAT for the whole site.
Delivery of ready-mixed concrete
Deliveries of ready-mixed concrete to a site are also covered by attendance registration.
Meat sector
Activities in the meat sector fall under their own scheme, separate from the €500,000 construction threshold.
Maintenance and cleaning
Not covered by the construction threshold. The thresholds of the declaration of works apply here — and they are much lower.
And who on the site?
If the site is covered, the obligation applies to everyone working there: your own employees, self-employed workers and freelancers, subcontractors at every level, safety coordinators and site managers. As the main contractor, inspectors will also look to you for the registration of your subcontractors.
When does the registration obligation end?
- At provisional acceptance of the site.
- At the end of the contract.
- For works under warranty: at final acceptance.
Does the threshold change in 2027?
The change on 1 April 2027 is not about when you have to register, but how: check-out becomes mandatory, registration must happen in real time on site and every worker registers themselves. If you are covered today, you will be covered then too — with stricter rules.
Frequently asked questions about the obligation
From what amount is Checkinatwork mandatory?
For construction works on immovable property, the registration obligation applies to sites with a total value of €500,000 or more excl. VAT. For sites that started between 1 April 2014 and 29 February 2016, the threshold was still €800,000.
Does it concern my own share or the whole site?
The total value of the site, not your share of it. A subcontractor with a €20,000 contract on a €900,000 site must therefore still register their people.
What if the site only crosses the threshold later?
Then the registration obligation starts at that moment. You must register attendance as soon as the threshold is reached, even if that was not the case when the works started.
How do I know whether my site is covered?
The contractor who declared the works receives a letter from the NSSO stating that attendance must be registered on that site. They must then pass this on to every party involved on the site — often with a poster with a QR code at the site entrance.
Which works are not covered?
Maintenance and cleaning do not fall under the same threshold: the rules and thresholds of the declaration of works apply to them instead. Certain activities in agriculture, horticulture and forestry are also explicitly excluded. Outside construction, the registration obligation does apply to the delivery of ready-mixed concrete and to the meat sector.
When does the registration obligation end?
At provisional acceptance, at the end of the contract or — for works under warranty — at final acceptance.
Does the threshold change in 2027?
The announced change is not about the threshold but about how you register: check-in and check-out, in real time on site, by the worker themselves. If you are covered today, you will be covered in 2027 too — with stricter rules.
Read more
- What is Checkinatwork (CIAW)?
- Registering for Checkinatwork with the NSSO
- Declaration of works or Checkinatwork: what's the difference?
- Adding a subcontractor to Checkinatwork
This page is general information, not legal advice. The official thresholds and exceptions are published by the NSSO on socialsecurity.be; check your specific site with your payroll provider (social secretariat).