Belgium Unfair Dismissal: CAO 109 and the Right to Know Why You Were Fired (2026)

Belgian law does not require an employer to show "just cause" for an ordinary dismissal the way some other countries do, but it does prohibit a dismissal that is kennelijk onredelijk, manifestly unreasonable, or licenciement manifestement déraisonnable in French. That standard, and the indemnity attached to it, comes from a single collective agreement: Collectieve Arbeidsovereenkomst nr. 109, Convention Collective de Travail n° 109, universally shortened to CAO 109 or CCT 109, concluded within the Nationale Arbeidsraad, the Conseil National du Travail.

CAO 109 does two separate things, and treating them as one misstates the law. It creates a right to ask why you were dismissed and get a real answer, backed by its own flat penalty. And, separately, it lets a court award an indemnity of 3 to 17 weeks' pay, on top of ordinary severance, where the dismissal itself is found manifestly unreasonable. This page covers both. How severance itself is calculated, including what pay counts and how the RVA / ONEM treats it, is on the severance pay page.

Information last verified on 22 July 2026. This page provides general legal information and does not constitute legal advice in an individual case.

What counts as kennelijk onredelijk

A dismissal is manifestly unreasonable under CAO 109 where it rests on grounds unconnected to the employee's fitness or conduct, and not dictated by the operational needs of the business, of a kind no normal and reasonable employer would ever have decided on. The arbeidsrechtbank, the tribunal du travail, is the court that applies this test, and it awards an indemnity scaled to how far the dismissal departs from that standard, from 3 weeks' pay at the low end to 17 weeks' pay at the high end.

This indemnity sits on top of, not instead of, the ordinary severance owed for the notice period itself. A dismissal can be entirely lawful in the sense that proper notice or severance was paid, and still attract a CAO 109 indemnity if the underlying decision to dismiss fails this reasonableness test.

Who is covered

CAO 109 applies to private-sector employees with at least 6 months' seniority with the employer. Successive contracts in the same role count toward that threshold, provided they were for the same function.

Who is excluded

The agreement carries a full list of exclusions. CAO 109 does not apply to:

• Temporary agency workers, for the duration of their agency assignment.
• Employees under a student contract.
• Dismissals connected to the SWT/RCC early-unemployment scheme, formerly known as brugpensioen.
• Dismissals given once the employee has reached statutory pension age and pension entitlement.
• Closures and collective or multiple dismissals, which follow their own separate information-and-consultation procedure rather than the individual rules here.
• Dismissals already subject to a specific statutory or CCT procedure, such as for social-election-protected staff representatives or prevention advisers. A different and larger protection applies to these categories instead, covered on the severance pay page.

Dismissal for urgent cause is excluded too, but only from the right-to-know-the-reasons chapter below, since article 35 of the wet van 3 juli 1978 already requires the employer to give the specific reasons within three working days of the dismissal. An urgent-cause dismissal is not automatically excluded from the reasonableness test itself; it can still separately be tested for whether the dismissal was in fact justified.

The right to know why you were dismissed

CAO 109 also creates a right to be told the concrete reasons for a dismissal, separate from whether that dismissal turns out to be reasonable. A dismissed employee can request those reasons in writing within 2 months of the contract ending, where it ended immediately, or, where notice was given, within 6 months of the notice being given, capped at 2 months after the contract actually ends. Once requested, the employer has 2 months to answer with the concrete reasons.

An employer that fails to answer within that window, or answers without actually giving the concrete reasons, faces a flat civil penalty of 2 weeks' pay, owed regardless of the actual harm caused. This 2-week penalty is cumulable with any indemnity awarded for a manifestly unreasonable dismissal above; the two are assessed separately, and both can apply to the same dismissal.

The two mechanisms answer different questions. The reasons-request procedure asks only whether the employer explained itself properly and on time. The kennelijk onredelijk test asks whether the underlying decision to dismiss was one a reasonable employer would ever have made.

Protected categories: a different, larger protection

Some workers sit outside the CAO 109 scale entirely. Pregnant workers, union delegates and candidates in social elections, prevention advisers, and workers on time credit or thematic leave are protected by separate statutory instruments carrying their own fixed indemnities, which can be considerably larger than a CAO 109 award and follow their own procedures rather than the reasonableness test on this page. Those protections, and the specific figures attached to each category, are set out on the severance pay page.

Sector agreements sit above this too

CAO 109 itself is a federal collective agreement, but it does not exhaust what a sector can agree. A paritair comité, a commission paritaire, can conclude its own collective agreements on dismissal procedure and notice that improve on the federal floor, and where such an agreement is made generally binding by Royal Decree it applies to every employer within that committee's scope. Checking whether one applies is worthwhile before assuming CAO 109 and the ordinary notice scale are the whole picture for a given employer.

This page provides general information about Belgian dismissal law and does not constitute legal advice for an individual case. Confirm current rules against CAO nr. 109 and the FOD Werkgelegenheid / SPF Emploi before relying on them, and check whether a protected category or a sectoral collective agreement changes the picture for your situation.