| Month | Health index (2013=100) |
|---|
- Base rent = the original rent agreed in the lease (not last year's indexed amount — always index from the contractual base rent).
- Starting index = the health index of the calendar month before the lease entered into force.
- New index = the health index of the calendar month before the anniversary of the lease.
- Indexation is not automatic: the landlord must request it (in writing) and it applies at most 3 months retroactively.
- A valid EPC/EPB/PEB certificate and a registered lease are required to index.
▸ FAQ — Frequently asked questions
What is rent indexation in Belgium?
Rent indexation is the yearly adjustment of the rent to the cost of living, measured by the health index. It is allowed once per year, at the earliest on the anniversary of the lease, and only if the lease is in writing and registered. The landlord must request it; it is never automatic and applies at most three months back in time.
Which health index should I use?
Use the ordinary health index (gezondheidsindex / indice santé), not the smoothed/4-month average used for wages and benefits. The starting index is the value of the month before the lease started; the new index is the value of the month before the anniversary. Both must use the same base year so the ratio is correct — this tool uses base 2013 = 100.
Why does my EPC label matter?
Since the 2022 energy crisis, all three regions linked indexation to the energy performance of the dwelling. Brussels still applies a correction factor for poor labels (E/F/G) on older leases; Flanders limits indexation for labels D/E/F (and bans it for E/F from 2028); Wallonia's PEB limitation has expired. Energetically efficient homes (A+/A/B/C) can always be indexed in full.
Do I index from last year's rent or the original rent?
Always from the base rent stated in the lease and the starting index of the contract — not from last year's already-indexed amount. The formula naturally compounds because the new index keeps rising, so re-indexing from the original base each year produces the correct cumulative figure.
Is this calculation legally binding?
No. This is an indicative tool, not legal advice. Belgian rent law is regional and changes regularly. Always confirm with the official regional rent calculator and check the exact wording of your lease before applying or paying an indexation.