Rent indexation in Brussels, August 2025
Your lease has its anniversary in August 2025? Here is the health index to use, the formula, and what Brussels adds on top.
Which index for an anniversary in August 2025
Belgian law (Civil Code art. 1728bis) reads the health index of the month BEFORE the anniversary: for August 2025, that is July 2025. The starting index is the one of the month before the lease was signed.
No intermediate rounding: the ratio is applied in full, then the result is rounded to the cent.
| Lease signed in | Starting index | Rent from August 2025 | Since signature |
|---|---|---|---|
| August 2024 | 132.84 (July 2024) | €1,020.78 | +2.08 % |
| August 2023 | 128.22 (July 2023) | €1,057.56 | +5.76 % |
| August 2022 | 122.35 (July 2022) | €1,108.30 | +10.83 % |
| August 2021 | 112.18 (July 2021) | €1,208.77 | +20.88 % |
| August 2020 | 110.16 (July 2020) | €1,230.94 | +23.09 % |
Before any regional correction. A lease indexed every year lands on the same figure whatever the path: the ratio always runs from the starting index.
What Brussels adds
Housing is regional. Three regions, three answers to the same question: does a poor energy certificate still weigh on the indexation of an older lease?
The indexed rent is multiplied by the official correction factor the Region publishes for the anniversary month, one row per month, one column for E, one for F/G (Code bruxellois du Logement, art. 224/2). The calculator carries the current table. Since 1 January 2025 the lease must also be registered with Bruxelles Logement, or no indexation is due at all.
Indexed in full, on the formula above. The only conditions left are the national ones: a registered lease, a certificate handed to the tenant, a written request.
Indexation is never automatic: it applies from your written request, and reaches back at most three months. An anniversary in August 2025 claimed late leaves money on the table for good.
An unregistered lease cannot be indexed, and neither can one whose tenant never received the energy certificate. Both are checked before the figure in the calculator.
Same month, other regions:
Figures as published by Statbel and read on September 30, 2026.
Your rent, your dates, the exact figure
The free calculator applies the formula, the regional correction and the three-month cap to your lease, and emails you the letter to send.
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