Mandatory Flatshare Agreement in Brussels: What You Need to Know

In Brussels, flatsharing is not just an informal arrangement between friends: it is a regime governed by the Brussels Housing Code (art. 2 §1 35°). As soon as several people sign a joint lease under the flatshare regime, the law requires a flatshare agreement to be drawn up between flatmates — a document separate from the lease that organises their shared living arrangements and mutual commitments.

Flatshare Agreement vs. Lease: What's the Difference?

The lease ties the flatmates to the landlord: it sets the total rent, the duration, and the obligations towards the landlord. The agreement, on the other hand, ties the flatmates to each other: splitting charges, house rules, and the terms for moving out and in.

The landlord is not a party to the agreement. They do not sign it and have no say over its content: it is an arrangement internal to the flatshare.

What the Agreement Should Cover

• The split of rent and charges between flatmates.
• The terms for a flatmate moving out or in.
• The split of the rental deposit.
• House rules for shared living (optional, but strongly recommended).

A Flatmate Moving Out

A flatmate who wants to leave the flatshare must give at least two months' notice. No automatic penalty is due if they put forward a replacement accepted by the other flatmates, or show they actively searched for one.

Otherwise, the outgoing flatmate remains jointly and severally liable for the rental debts for six months from the date their notice period ends. After that period, their future obligations and joint liability with the other flatmates are automatically extinguished (Brussels Housing Code, art. 260 §3).

The agreement does not change this legal rule, but it lets flatmates settle in advance what is actually up to them: who looks for the replacement, how shares get recalculated, and how everyone is protected if the move-out does not go as planned.

Flatsharing is defined there as the letting of a single dwelling to several tenants who make it their main residence and who have formalised their relationship in a flatshare agreement.

Brussels Housing Code, art. 2 §1 35° (paraphrased)

Why a Simple Downloaded PDF Is Not Enough

A static template does not survive the first change of flatmate. But a flatshare changes: someone leaves, someone else moves in, and the rent, charges and deposit shares all need recalculating — then everyone has to re-sign a consistent version.

A Word document or a downloaded PDF does none of that. You have to track it down, edit it by hand, hope the amounts add up and that no one is using an outdated version. That is exactly what a living agreement avoids — see what a complete agreement looks like.

Mettez votre coloc d'accord, noir sur blanc.

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