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Rent indexation in Flanders, May 2026

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

139.33
Health index, April 2026 (base 2013)
134.77
One year earlier, April 2025
+3.38 %
Over twelve months, the rise of a rent indexed last year

Which index for an anniversary in May 2026

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

Indexed rent = base rent × 139.33 ÷ 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 May 2026Since signature
May 2025134.77 (April 2025)€1,033.84+3.38 %
May 2024130.85 (April 2024)€1,064.81+6.48 %
May 2023126.70 (April 2023)€1,099.68+9.97 %
May 2022119.59 (April 2022)€1,165.06+16.51 %
May 2021110.93 (April 2021)€1,256.02+25.60 %

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 Flanders 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?

Flanders, EPC D, E or F on a lease in force before 01/10/2022

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:

EPC D× 0.9719
EPC E or F, or no certificate× 0.9439
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 May 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.

← April 2026 All of 2026 June 2026 →

Same month, other regions:

BelgiumBrusselsWallonia

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 May 2026, April 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.