Check-in-at-work (CIAW) in Belgium: The Complete Guide for Dutch Companies

How to handle Limosa, daily site registration, and automated compliance with Suivo

Your company has just won a contract on a Belgian construction site. The planning is in place, the crew is ready  but before anyone crosses the border, there’s a critical administrative step that many Dutch contractors underestimate: Checkinatwork (CIAW).

CIAW is Belgium’s mandatory electronic attendance registration system for qualifying construction sites, ready-mix concrete delivery and meat processing (cleaning has its own system, Check in and Out at Work). For Dutch companies, the process is more complex than for Belgian firms because of an essential extra requirement: the Limosa declaration. Miss either step  the pre-registration or the daily check-in  and you face a criminal fine of €2,000 to €20,000 or an administrative fine of €1,000 to €10,000 for every worker involved.

This guide walks you through every step: what CIAW is, how it connects to Limosa, what triggers an inspection, and how to automate the entire process so your teams can focus on the actual work.

Get started with automated compliance via Suivo’s Check-in at Work solution.

Quick Navigation

• What Is Checkinatwork (CIAW)?
• Which Sectors Require CIAW?
• The Limosa Connection: Why Dutch Companies Have an Extra Step
• Step by Step: From Limosa to Daily Check-In
• Fines and Inspection Consequences
• Automating CIAW with Suivo
• Quick Compliance Checklist
• Frequently Asked Questions

What Is Checkinatwork (CIAW)?

Checkinatwork is the Belgian government’s electronic attendance registration system, managed by the NSSO (RSZ  Rijksdienst voor Sociale Zekerheid). Its purpose is to combat undeclared work, social fraud, and unsafe working conditions by creating real-time visibility into who is present at which location.

The rule is straightforward: every person performing work on a qualifying Belgian site must check in via the CIAW system before work begins  not upon arrival, but before the first task starts. This applies every single working day.

For Belgian companies, check-in happens using the national social security number. For Dutch and other foreign companies, the process requires an additional step: the Limosa declaration, which we’ll cover in the next section.

Which Sectors Require CIAW?

CIAW applies to construction (including ready-mix concrete delivery to qualifying sites) and to meat processing. Cleaning has its own system, Check in and Out at Work (CIAO), shown below for comparison. From 1 April 2027, construction works and ready-mix concrete delivery on sites of €500,000 or more excl. VAT also move from CIAW to CIAO, which registers both arrival and departure; from that date construction attendance can no longer be registered in CIAW.

Sector	Threshold	Scope
Construction	Projects ≥ €500,000 (excl. VAT) with RSZ site declaration	All real estate works: building, renovation, infrastructure, demolition
Meat processing	Always mandatory, regardless of value	All activities in meat processing facilities
Cleaning	Not CIAW: since 1 September 2024 under Check in and Out at Work (CIAO), where the cleaning falls under the declaration-of-works thresholds	Third-party cleaning of immovable property (CIAO system)

⚠️ Who must register? Everyone who sets foot on a qualifying site must be checked in before work starts  no exceptions. This includes your own employees, freelancers, self-employed subcontractors, staff from subcontractors, and temporary agency workers.

The Limosa Connection: Why Dutch Companies Have an Extra Step

This is where many Dutch contractors make a costly mistake. Belgian companies check in using their national social security number. Dutch and other foreign companies cannot  instead, they need a Limosa declaration for every worker before entering Belgium.

The Limosa declaration (L1) is a mandatory pre-registration with the Belgian authorities, notifying them who will be working, where, and for how long. Without a valid Limosa declaration, your employee simply cannot be registered in the CIAW system.

❌ The most common mistake: Many Dutch companies believe that completing the Limosa declaration means they are fully compliant. That is an expensive misconception. Limosa is the one-time pre-registration. CIAW is the daily check-in on site. Missing the daily registration puts you immediately at risk of a fine  even if your Limosa paperwork is perfect.

Aspect	Limosa Declaration	CIAW Registration
What it is	One-time pre-registration with Belgian authorities	Daily attendance registration on site
When	Before the worker enters Belgium	Every working day, before work starts
Frequency	Once per assignment (may need renewal)	Every single day on site
Managed by	Belgian Federal Government (Limosa portal)	NSSO (RSZ) via Checkinatwork system
Output	L1 document with Limosa number + QR code	Digital registration in RSZ database
Without it	Worker not permitted on site	Fine of €1,000–€10,000 (administrative) or €2,000–€20,000 (criminal) per worker involved

Step by Step: From Limosa to Daily Check-In

Here’s the complete workflow for a Dutch company sending workers to a Belgian site:

Step 1: Submit the Limosa declaration before departure

Before any worker crosses the border, submit the Limosa declaration via the official Limosa online portal. You’ll declare who is going, which site they’ll work on, and for how long. This must be completed before the employee arrives in Belgium.

Step 2: Receive and store the L1 documents

After the declaration, you receive an L1 document for each employee containing a unique Limosa number and QR code. Store these securely  workers will need them for daily CIAW registration, and inspectors may request them on site.

Step 3: Obtain the RSZ site number from your Belgian client

Your Belgian client or main contractor must provide you with the official RSZ site number for the project. This number links your workers’ registrations to the correct construction site in the NSSO database.

Step 4: Check in every working day before work starts

Each worker uses their Limosa number to register in the CIAW system every morning, before the first task begins. This can be done via the RSZ website, a mobile app, or  much more reliably  through an automated system like Suivo (covered in the next section).

Fines and Inspection Consequences

The Belgian Labour Inspectorate conducts regular and unannounced checks on construction sites. The penalties for non-compliance are substantial:

• €2,000 to €20,000 criminal fine or €1,000 to €10,000 administrative fine (level 3), multiplied by the number of workers involved
• Repeat violations can lead to higher sanctions and work stoppages on site
• Clients and main contractors have their own duty to make sure their subcontractors’ workers are registered, and can be fined for failing it

Given that an average construction project has dozens of workers on site, the total cost of a serious inspection can escalate to tens of thousands of euros within a single day. For Dutch companies, there’s an added risk: if your Limosa declarations are expired or missing, the CIAW registration cannot be completed at all  meaning every worker on site is in violation.

Automating CIAW Registration with Suivo

Manual check-ins  every morning, for every employee, via the RSZ website  are slow, error-prone, and impractical for multi-site operations. Most professional contractors solve this with Suivo: a Belgian IoT platform with a direct, official connection to the RSZ database.

Here’s how the automated workflow looks:

1. Link employee data and Limosa numbers in the Suivo Platform

Enter your Dutch employees’ details in Suivo’s central dashboard and link each person’s unique Limosa number (from their L1 document) to their profile. This is the foundation of correct CIAW registration.

2. Define the RSZ site using geofencing

Draw a virtual boundary around the Belgian work location in Suivo’s map interface. Attach the official RSZ site number to that geofence. When a worker enters the zone, Suivo knows exactly which site they’re arriving at.

3. Choose your registration method

Suivo offers three flexible options to match different site types:

•   Vehicle hardware (RFID)  workers scan their badge in the work van. When the vehicle’s GPS tracker enters the site geofence, Suivo automatically registers everyone on board in CIAW

•   Suivo App  workers tap “Check in” on their smartphone. GPS verifies the location and transmits the data instantly

•   Site terminal  a fixed badge point at the site entrance. Workers scan their badge or Limosa QR code. Ideal for large, permanent sites with multiple teams

4. Automatic submission to RSZ

After each check-in, Suivo transmits all data via a secure connection to the RSZ in real time. No manual entry on the RSZ website, no CSV uploads, no missed registrations.

5. Live monitoring from the Netherlands

Your HR team or planner can see in the Suivo dashboard exactly who has successfully checked in (green status) and where there’s an error  for example, a missing or expired Limosa number (red status). You can act immediately, before an inspector arrives on site.

Without Automation	With Suivo
Manual RSZ login every morning for every worker	Automatic registration via badge, app, or sitepole
Easy to forget  one missed day = one fine	GPS-triggered: registration happens as workers arrive
No visibility from the Netherlands office	Live dashboard showing all sites and all workers
Expired Limosa discovered only during inspection	Real-time alerts for missing or expired Limosa numbers
Paper L1 documents scattered across sites	All Limosa data linked centrally to employee profiles
Hours of admin per week	Zero manual entry on site

Quick Compliance Checklist for Dutch Companies

Use this checklist before your team crosses the border:

Action	Status	Owner
Limosa declaration submitted for all employees going to Belgium		HR
L1 documents received with Limosa numbers and QR codes per employee		HR
Limosa numbers entered in Suivo and linked to employee profiles		HR / Admin
RSZ site number obtained from Belgian client or main contractor		Project Mgr
Geofence created in Suivo with correct RSZ site number attached		Admin / IT
Registration method chosen and tested (app, RFID, or terminal)		Operations
HR team trained on monitoring the Suivo dashboard		HR
Process for Limosa renewals defined (before expiry)		HR

Frequently Asked Questions

Can a Dutch company register in CIAW without Limosa?

No. For foreign workers, the Limosa declaration is a prerequisite for CIAW registration. Without a valid Limosa number, the CIAW system cannot identify the worker. The Limosa declaration must be completed before the worker arrives in Belgium.

Does the Limosa declaration need to be renewed?

Yes. A Limosa declaration is valid for the period specified in the application. If a project runs longer than declared, extend the existing declaration in the Limosa online service before the declared period ends; a worker who returns for a new assignment needs a new declaration. Suivo can flag expiring Limosa numbers so your HR team can renew them before they lapse.

What if my worker forgets to check in one morning?

A single missed check-in constitutes a violation and can result in a criminal fine of €2,000 to €20,000 or an administrative fine of €1,000 to €10,000 for each worker involved. This is why automation is critical  GPS-triggered registration via Suivo means check-ins happen as workers arrive, without relying on individual memory.

Is the main contractor liable if my company doesn’t comply?

The main contractor can be fined as well. The client and each contractor in the chain have their own CIAW duty: they must make sure the workers of their subcontractors are registered, either by registering them or by agreeing clearly who does it. A contractor that fails to do so risks the same level 3 fine per worker involved.

Can I use Suivo if I only occasionally work in Belgium?

Yes. Suivo is scalable  it works for a single employee on one site just as well as for full crews across multiple Belgian projects. The platform doesn’t require a long-term commitment for occasional use, making it practical for Dutch companies that work in Belgium periodically.

Does Suivo also handle time registration and payroll?

Yes. Beyond CIAW compliance, Suivo’s platform includes time registration, scheduling, and payroll integration. The same attendance data that feeds the RSZ also flows into your payroll system  eliminating double data entry and ensuring every worked hour is accounted for.

Working in Belgium? Make CIAW compliance automatic.

Book a free demo and see how Suivo handles Limosa, CIAW, and attendance registration from one platform.

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