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Rent indexation in Brussels, October 2026

Your lease has its anniversary in October 2026? Here is the health index to use, the formula, and what Brussels adds on top.

140.67
Health index, September 2026 (base 2013)
135.26
One year earlier, September 2025
+4.00 %
Over twelve months, the rise of a rent indexed last year

Which index for an anniversary in October 2026

Belgian law (Civil Code art. 1728bis) reads the health index of the month BEFORE the anniversary: for October 2026, that is September 2026. The starting index is the one of the month before the lease was signed.

Indexed rent = base rent × 140.67 ÷ starting index

No intermediate rounding: the ratio is applied in full, then the result is rounded to the cent.

For a base rent of €1,000.00, by signature date of the lease
Lease signed inStarting indexRent from October 2026Since signature
October 2025135.26 (September 2025)€1,040.00+4.00 %
October 2024132.41 (September 2024)€1,062.38+6.24 %
October 2023127.52 (September 2023)€1,103.12+10.31 %
October 2022124.92 (September 2022)€1,126.08+12.61 %
October 2021112.29 (September 2021)€1,252.74+25.27 %

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?

Brussels, PEB E, F or G on a lease in force before 14/10/2022

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.

Labels A to C, and every lease signed since autumn 2022

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.

Ask in writing, within three months

Indexation is never automatic: it applies from your written request, and reaches back at most three months. An anniversary in October 2026 claimed late leaves money on the table for good.

Registered lease, certificate handed over

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.

← September 2026 All of 2026

Same month, other regions:

BelgiumFlandersWallonia

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.

Open the calculator →

Free · No sign-up · Official figures

Questions, answered

When is the health index of a month published?
Statbel publishes it in the last days of the month itself. The index you need for an anniversary in October 2026, September 2026, is therefore known before the anniversary arrives.
Signature date or effective date?
The anniversary follows the date the lease took effect; the starting index follows the month before signature. For most leases they are the same month, when they differ, the calculator takes both.
Can the indexation be lower than last year’s?
Yes: the ratio follows the index, which can fall. Nothing forces a landlord to apply a downward indexation, but a tenant may ask for it under the same article.