Rent indexation in Belgium, December 2025
Your lease has its anniversary in December 2025? Here is the health index to use, the formula, and what each region adds on top.
Which index for an anniversary in December 2025
Belgian law (Civil Code art. 1728bis) reads the health index of the month BEFORE the anniversary: for December 2025, that is November 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 December 2025 | Since signature |
|---|---|---|---|
| December 2024 | 133.22 (November 2024) | €1,024.55 | +2.45 % |
| December 2023 | 128.55 (November 2023) | €1,061.77 | +6.18 % |
| December 2022 | 127.44 (November 2022) | €1,071.01 | +7.10 % |
| December 2021 | 115.20 (November 2021) | €1,184.81 | +18.48 % |
| December 2020 | 109.91 (November 2020) | €1,241.83 | +24.18 % |
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 each region 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.
Between 01/10/2022 and 30/09/2023 Flanders indexed label D at 50 % and E/F not at all, and forbids catching up afterwards (decree of 3 October 2022, art. 4). Every later indexation is multiplied by a factor built from the health index of that frozen year. For a lease whose anniversary falls in this month:
Between 01/11/2022 and 31/10/2023 Wallonia indexed PEB D at 75 %, E at 50 % and F/G not at all; since 01/11/2023 the base rent and base index are those of that capped year, so the lost share is never recovered (decree of 19 October 2022). Expressed as a factor on a full indexation, for a lease whose anniversary falls in this month:
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 December 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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