When can you index the rent in Belgium? (deadlines and rules 2026)
Last reviewed on 2026-06-10 · reading time ± 3 min
Indexation is allowed once per lease year, at the earliest on the anniversary of the entry into force of the lease. Not on 1 January, then (unless your contract happened to start on 1 January), and not on the anniversary of the signing.
The right moment
Say your contract was signed on 15 March and entered into force on 1 April. Then you may index every year from 1 April. The new index is the health index of the month before that anniversary — March in this example. Statbel publishes a month's index figure at the end of that same month, so you can usually only do the final calculation a few days before the anniversary.
How far back?
Forgot to index? The indexation works back a maximum of three months from your written request. If you request in September an indexation that was already possible since April, you can only charge the higher amount from June–July (three months before your request), not from April. The "lost" months are gone for good — setting an annual reminder pays off.
Conditions
- The contract is in writing. With a verbal lease, indexation is in principle excluded.
- The contract does not exclude indexation. (Since the regional residential lease decrees, you may index unless the contract forbids it; for older contracts under the old Civil Code, the contractual terms apply.)
- In Brussels: the contract is registered and the EPB certificate was presented to the tenant. Without both, indexation is not allowed.
- In Flanders and Wallonia, the energy label (EPC/PEB) affects the calculation for contracts from before the 2022–2023 energy freeze.
Which index?
Always the health index (a derivative of the consumer price index without, among other things, tobacco, alcohol and motor fuels), and always the same base for numerator and denominator. Our tool calculates in base 2013=100 with the official Statbel series. View the current index figures here.
The calculator automatically determines the right starting and new index for your region and contract date, and generates a ready-made letter to go with it.