Every day, cleaning and construction companies register their staff via the official NSSO QR code or via a commercial Check In & Out solution. For most companies, the story ends there. Not for the NSSO: after every registration, the NSSO runs automatic checks, and that is exactly where most errors arise. Not out of unwillingness, but because of familiar, everyday situations on site.
The three most common error codes in practice
- CAW_1 — Registration without corresponding employment. The registration was sent, but the NSSO finds no active Dimona at that moment. Usually the result of a late Dimona declaration, an incorrect identification, or a temporary desynchronisation between systems.
- CAW_10 — Duplicate registration. There are multiple check-in or check-out events for the same person at the same site. Often caused by human error, a slow internet connection, or a duplicate submission from the app used.
- CAW_25 — Registration outside the valid employment window. The registration time falls outside the stated contractual working hours. This typically arises when a schedule change was not communicated, during a shift change, or because of an incorrectly entered time.
Where these errors usually come from
- Dimona is only submitted after the employee has already started, instead of before.
- A confirmation screen or offline buffering is missing, causing a registration to be accidentally sent twice.
- Schedules are changed on site but not updated in the Check In & Out system.
- Employees switch between shifts or sites without the registration moving with them.
- Subcontractors register independently, but their registrations are not monitored as closely as those of the company's own employees.
What it can cost if it goes wrong
Since 1 May 2025, the transition period without sanctions has ended: inspections and fines are now actively enforced. In the event of a breach of the CIaO registration obligation, you risk an administrative fine of €800 to €8,000, or a criminal fine of €1,600 to €16,000 — per employee involved. If, for example, 5 employees are found without correct registration at a single location, this can already amount to €15,000–€20,000 in a single inspection.
These are figures from the Social Criminal Code and the official NSSO documentation, not an estimate by CIAO Assist. For a concrete assessment of your situation, we recommend consulting a social secretariat or a lawyer.
How to prevent this structurally
- Always complete Dimona before the first registration, never after.
- Check that your Check In & Out solution has a confirmation screen and offline buffering, to avoid duplicate submissions.
- Synchronise schedule changes in real time with the registration system, including last-minute shift changes.
- Monitor subcontractors as strictly as your own employees — responsibility does not stop at the handover.
- Don't wait for an inspection to discover which error codes are present. Periodically check what the NSSO actually registers, not just what you send yourself.
Registering is not the same as registering correctly. The difference lies in the error codes the NSSO is already recording in the meantime — and which only become visible once someone looks.