No, the solidarity clause is optional
The solidarity clause is not mandatory in Belgian leases. It must be explicitly included in the lease agreement to be enforceable. When present, each co-tenant is liable for the entire rent amount. Without it, each co-tenant is only responsible for their individual share. The clause is common in shared housing leases but must be carefully balanced.
Under Belgian civil law, solidarity between debtors is never presumed — it must be expressly stipulated in the contract (Article 1202 of the old Civil Code, now Article 5.163 of the new Civil Code). This means that unless the lease explicitly states that the co-tenants are jointly and severally liable, each tenant is only responsible for their proportional share of the rent.
The solidarity clause is particularly relevant in shared housing situations where multiple tenants share a single lease. It provides the landlord with maximum financial security but can create significant risk for individual tenants.
How the solidarity clause works
With a solidarity clause:
- The landlord can claim the full rent from any single co-tenant
- If one co-tenant does not pay, the others must cover the difference
- The paying co-tenant can then seek reimbursement from the defaulting co-tenant
- The clause survives the departure of a co-tenant until the lease amendment is signed
Without a solidarity clause:
- Each co-tenant is only liable for their proportional share
- If one co-tenant does not pay, the landlord can only pursue that specific tenant
- The other co-tenants are not affected
- The landlord bears the risk of non-payment
BailBelgique allows you to choose whether to include a solidarity clause in your shared housing lease. The platform explains the implications of each option and generates appropriate language for the chosen approach.
Pros and cons for landlords and tenants
| Perspective | With solidarity clause | Without solidarity clause |
|---|---|---|
| Landlord security | Maximum (can claim full rent from anyone) | Lower (must pursue each tenant individually) |
| Tenant risk | High (liable for full rent) | Lower (only own share) |
| Vacancy coverage | Co-tenants cover empty room | Landlord absorbs the loss |
| Tenant flexibility | Lower (harder to leave) | Higher (easier to leave) |
| Attractiveness | May deter tenants | More attractive to tenants |
The solidarity clause should ideally be combined with an individual exit clause to balance landlord security with tenant flexibility. This allows a co-tenant to leave without affecting others while maintaining rent coverage through a replacement.
If you sign a lease with a solidarity clause, understand that you are potentially liable for the entire rent — not just your share. This liability continues until you are formally removed from the lease via a lease amendment. Simply moving out does not end your financial obligation.
Regional specifics
Brussels-Capital Region
The Brussels Housing Code does not make the solidarity clause mandatory for shared housing. However, it provides that when a co-tenant leaves and proposes a valid replacement, the departing co-tenant is released from solidarity obligations. This limits the duration of solidarity exposure.
Wallonia
The Walloon Residential Lease Decree does not impose or prohibit the solidarity clause. It is left to the contractual freedom of the parties. Walloon courts apply the general civil law rule: solidarity must be explicit.
Flanders
The Flemish Housing Rental Decree does not mandate the solidarity clause. However, Flemish courts have emphasized that the clause must be clear and unambiguous to be enforceable. A vague reference to “shared responsibility” may not suffice.
Belgian Civil Code, art. 5.163 (formerly art. 1202) — Solidarity is never presumed and must be expressly stipulated. Regional housing legislation does not override this principle but may limit the duration of solidarity in shared housing.