Belgium: you must tell the works council three months before

From 50 staff, CAO 39 requires written information and consultation three months before you introduce technology with collective impact.

This is the Belgian obligation that surprises people most, because nothing in the international AI literature mentions it and it is not in the AI Act.

Collective labour agreement no. 39 of 13 December 1983. If your company normally employs at least 50 people, and you introduce a new technology with significant collective consequences for employment, work organisation or working conditions, you must give written information and hold a consultation at the latest three months before implementation starts.

The information goes to the works council. If there is no works council, to the union delegation. If there is neither, to the committee for prevention and protection at work (CPBW/CPPT).

Why this catches AI projects specifically

A pilot rarely feels like "introducing a new technology". It feels like giving four people a tool to try. But the moment it changes how work is allocated, monitored, or evaluated — which is exactly what a useful AI pilot does — it is squarely inside the scope of the agreement.

The three months are not a notice period you can serve at the end. They run before implementation starts. A team that decides in September to go live in October has already lost the option of doing this properly.

What the information has to cover

Two things, and the second is the one people forget:

The nature of the technology and why you are introducing it.
The nature of the social consequences — and a consultation about them.

"We are piloting an AI assistant" does not satisfy the second. What changes for the people doing the work? Does it alter how output is measured? Does anyone's role narrow? Is anything now monitored that was not monitored before?

What this costs you if you skip it

Less than you might fear, and more than you would like. There is no dramatic penalty attached to CAO 39 itself. What it does is hand your works council a legitimate grievance at precisely the moment you need their cooperation, and it turns a rollout question into a social-dialogue conflict. In a Belgian company that is the expensive part.

How to make it a help rather than a tax

Run the consultation as the pilot's design review, not as an announcement.

The questions a works council asks — what happens to the people whose work this changes, how will performance be judged now, what happens to the data about individuals — are the same questions that determine whether the pilot survives contact with reality. Teams that answer them in month one build something people use. Teams that answer them in month six rebuild.

Practical sequence that works:

When	What
Month 0	Decide the use case and the KPI. Draft the social-impact note.
Month 0	Written information to the council; put it on the agenda.
Months 0–3	Consultation. Build in parallel — you are not blocked, only the go-live is.
Month 3	Implementation starts, with the council already informed.

The build does not have to wait. Only the introduction does.

Under 50 employees

The agreement does not apply, and most Belgian companies sit here. The obligation disappears; the reasoning does not. The failure mode for a small company is identical — a tool nobody adopted because nobody was asked — it just arrives without a legal framing attached.