A new tenant can be added via an addendum
Yes, a new tenant can be added to an existing lease by signing a written addendum. All parties must consent: the landlord, all existing tenants, and the new tenant. The addendum should address joint and several liability, rent sharing, and the rental deposit. It must be registered with the FPS Finance.
Adding a tenant to an existing lease is a modification of the contract that requires the agreement of all parties. The landlord cannot be forced to accept a new tenant, and the existing tenant cannot unilaterally add someone to the lease. The principle of contractual freedom means all parties must freely consent.
The addendum creates a new contractual relationship: the new tenant becomes a party to the lease with the same rights and obligations as the original tenant(s), unless the addendum specifies otherwise.
How to add a tenant to an existing lease
The addendum should contain:
- Reference to the original lease — date, address, parties
- Identity of the new tenant — full name, date of birth, national register number
- Effective date — when the new tenant joins the lease
- Joint and several liability — whether all tenants are jointly liable for the full rent
- Rent sharing — how the rent is divided (internal arrangement)
- Rental deposit — adjustment of the deposit if needed
- Signatures — all parties (landlord, existing tenants, new tenant)
| Step | Action | Responsible |
|---|---|---|
| 1 | Draft the addendum | Landlord or parties jointly |
| 2 | Landlord verifies new tenant | Landlord |
| 3 | All parties sign | All |
| 4 | Register with FPS Finance | Landlord (free for primary residence) |
| 5 | Update rental deposit if needed | All |
Always include a joint and several liability clause (solidarite) in the addendum. Without it, each tenant is only liable for their share of the rent, which increases the landlord’s risk if one tenant fails to pay.
Legal implications of adding a tenant
Adding a tenant has several important consequences:
- Joint and several liability — if included, each tenant is liable for the full rent. The landlord can claim the entire rent from any tenant
- Rental deposit — the landlord may require an increase in the rental deposit to reflect the additional occupant
- Notice period — the new tenant acquires the same termination rights as the original tenant
- End of lease — all tenants must agree to terminate, or each tenant can give individual notice (depending on the colocation framework)
- Inventory — a new interim inventory is recommended to document the property’s condition at the time of the new tenant’s arrival
The new tenant’s rights begin from the effective date stated in the addendum. They are not responsible for any obligations arising before that date, unless the addendum explicitly states otherwise.
Regional specifics
Brussels-Capital Region
The ordinance of 27 July 2017 provides a specific framework for colocation (shared housing). Brussels allows a colocation pact that facilitates tenant rotation without the landlord’s intervention for each change, provided the pact is annexed to the lease.
Walloon Region
The decree of 15 March 2018 also includes colocation provisions. Wallonia requires the landlord’s agreement for adding a new co-tenant unless the colocation pact provides otherwise.
Flemish Region
The Vlaams Woninghuurdecreet of 9 November 2018 contains detailed colocation rules. Flanders allows departing co-tenants to propose a replacement, which the landlord can only refuse on reasonable grounds.
Civil Code, art. 1134 (contractual freedom, modification by mutual agreement). Regional housing legislation on colocation provides specific frameworks for adding and removing co-tenants.