Indexation applies to shared housing leases
Yes, rent indexation applies to shared housing leases (colocation) just as for standard residential leases. The landlord has the legal right to annual indexation based on the health index. Indexation applies to the total rent, which is then divided among co-tenants. The landlord must request it in writing and it takes effect from the month following the request.
A shared housing lease (bail de colocation) is a primary residence lease, and all rules applicable to residential leases apply, including the right to rent indexation. Whether the lease is signed by all co-tenants jointly or through a colocation pact with individual annexes, the indexation mechanism remains the same.
The base rent for indexation purposes is the total rent stated in the lease, not the individual share of each co-tenant. The allocation of the indexed rent among co-tenants follows the internal sharing arrangement specified in the lease or colocation pact.
How indexation works for shared housing
| Element | Application |
|---|---|
| Base rent | Total rent in the lease |
| Index used | Health index |
| Calculation | Base rent x (New index / Base index) |
| Who receives notice | All co-tenants (or the designated contact person) |
| Who pays | Each co-tenant according to the sharing arrangement |
| Frequency | Annual, on the lease anniversary |
Example: A shared lease with a base rent of 1,200 EUR/month split equally among 3 co-tenants (400 EUR each). After indexation, the rent becomes 1,240 EUR. Each co-tenant now pays 413.33 EUR.
Include a clear rent-sharing clause in the colocation pact or lease. This prevents disputes when indexation increases the total rent. Specify whether each co-tenant pays an equal share or a proportional amount based on room size.
What happens when co-tenants change
When a co-tenant leaves and is replaced during the lease term:
- The base rent for indexation does not change — it remains the rent set at the start of the lease
- The base index does not change — it remains the index from the month preceding the lease start
- The new co-tenant benefits from the same indexation — they join the existing lease terms
- An addendum should be signed — documenting the change of co-tenant, referencing the current indexed rent
The replacement of a co-tenant does not restart the indexation calculation. The new tenant inherits the lease conditions, including any indexation already applied.
Regional specifics
Brussels-Capital Region
The ordinance of 27 July 2017 contains specific provisions for shared housing (colocation). Brussels recognises the colocation pact as a supplementary document to the lease. Indexation rules apply identically to shared housing leases.
Walloon Region
The decree of 15 March 2018 also addresses colocation. Wallonia provides a framework for the colocation pact, including provisions for tenant rotation. Standard indexation rules apply.
Flemish Region
The Vlaams Woninghuurdecreet of 9 November 2018 includes detailed provisions for shared housing. Flanders allows for a colocation pact (samenhuuraanvulling) that organises the relationship between co-tenants. Indexation follows the standard residential lease rules.
Regional housing legislation applicable to colocation (shared housing). Indexation follows the same rules as standard residential leases. Brussels ordinance 2017, Walloon decree 2018, Flemish decree 2018.