Indexation applies to verbal leases by law
Yes, rent indexation is possible for a verbal lease. The right to annual indexation based on the health index exists by law for all residential leases, whether written or verbal. However, a verbal lease creates practical difficulties in proving the base rent and the lease start date, which are essential for calculating the indexed amount.
Belgian law recognises verbal leases as valid contracts. Although regional legislation now requires a written lease, a verbal agreement between landlord and tenant still creates a binding lease relationship. The legal rights attached to a residential lease — including indexation — apply regardless of the form.
The challenge with a verbal lease is not the legal right to indexation but the practical ability to exercise it. The indexation formula requires a base rent and a reference date, both of which may be disputed when there is no written document.
Practical difficulties with verbal lease indexation
| Element needed | Written lease | Verbal lease |
|---|---|---|
| Base rent amount | Clearly stated | Must be proven |
| Lease start date | Clearly stated | Must be proven |
| Base index month | Derived from start date | Depends on proven start date |
| Indexation clause | Not required (legal right) | Not required (legal right) |
Without a written lease, the landlord must establish:
- The original rent amount — through bank transfer records, witness statements, or other evidence
- The lease start date — through registration records, utility connections, or municipal registration
- That the lease is for primary residence — through domicile registration
If the tenant disputes any of these elements, the matter must be resolved before the justice of the peace, which delays and complicates the indexation process.
If you have a verbal lease, it is strongly recommended to formalise it in writing as soon as possible. Either party can require the other to put the lease in writing. A written lease eliminates disputes about the base rent and start date, making indexation straightforward.
How to prove the base rent for indexation
Several types of evidence can establish the original rent of a verbal lease:
- Bank statements — regular monthly payments of a consistent amount to the landlord
- Payment receipts — if the landlord issued receipts for cash payments
- Tax declarations — the landlord’s tax filings may mention rental income
- Municipal registration — the tenant’s domicile registration confirms occupancy
- Witness statements — testimony from neighbours or other involved persons
- Utility records — connections in the tenant’s name with the property address
The most reliable evidence is consistent bank transfer records showing monthly payments of the same amount. Courts generally accept this as strong proof of the agreed rent.
Regional specifics
Brussels-Capital Region
The ordinance of 27 July 2017 requires a written lease but does not void verbal leases. A verbal lease in Brussels is subject to the same indexation rules. The tenant can request the justice of the peace to establish the lease terms if the landlord refuses to put it in writing.
Walloon Region
The decree of 15 March 2018 similarly requires a written lease. In Wallonia, either party can compel the other to formalise the lease in writing via the justice of the peace. Indexation rights apply from the actual start date of the tenancy.
Flemish Region
The Vlaams Woninghuurdecreet of 9 November 2018 mandates a written lease. Flanders provides that either party may request the justice of the peace to establish the terms of a verbal lease, including the base rent for indexation purposes.
Regional housing legislation guaranteeing the right to annual rent indexation for all primary residence leases. Civil Code provisions on verbal contracts. The legal right to indexation is independent of the lease form.