Most landlords in Belgium use Statbel's rent calculator to work out their indexed rent. It is an excellent tool, but it has limits. Here is how it works, which details you need to gather, and the cases where it will not get you to an answer.
A rent calculator works out your new rent based on the health index. The best known is Statbel's, the Belgian statistical office of the FPS Economy. You will find it on statbel.fgov.be under Consumer price index. You enter your base rent, the signing date and the date the lease took effect, choose your Region and your energy certificate, and receive the indexed rent. Since Statbel is the official source of the index figures, the result is legally usable.
Every correct calculator applies the same formula: indexed rent = base rent x new index / initial index. The base rent is the amount stated in your original lease, excluding charges. The new index is the health index for the month preceding the anniversary of your lease taking effect. The initial index depends on when your lease was concluded, and that is exactly where most mistakes arise.
Statbel distinguishes four situations. For leases concluded from 1 February 1994 onwards, the health index of the month before signing applies. For leases before that date, the index of the month before signing applies, but that is still the ordinary consumer price index. For leases concluded between 1 January 1981 and 31 December 1983, the index of the month preceding the adjustment or entry into force in 1983 applies. And for leases before 1 January 1981 the initial index is fixed: that of December 1982, namely 82.54.
For residential leases that took effect from 1 January 2019 and concern a main residence in the Flemish Region, a different rule applies. There the initial index is the health index of the month before the lease took effect, not before signing. Someone who signs in December and moves in on 1 January therefore uses a different figure than before. This change comes from the Flemish Residential Tenancy Decree and applies only to residential leases: for commercial leases, garages and warehouses the signing date remains decisive.
Not every lease may be indexed. Statbel sets out the rules clearly. For leases concluded after 31 May 1997, indexation is permitted unless the contract expressly excludes it. Important: for an oral lease concluded after that date, indexation is not permitted. For leases predating 28 February 1991 you may only index if both parties provided for it. A calculator does not check this for you: it simply calculates.
Most landlords in Belgium use Statbel's rent calculator to work out their indexed rent.
Statbel's tool works for leases that took effect from 1 January 1989. If your lease predates that, the calculator returns no result and Statbel refers you to its documentation to work out the calculation yourself. For leases concluded before 1 January 1984 the calculator is expressly unusable. Nor are the energy correction factors always fully built in: for Flanders and Brussels, Statbel refers you to separate tools provided by the Regions themselves.
Since the energy crisis, two Regions apply distinct rules. In Flanders, indexation has been permitted again since 1 October 2023 for homes without an EPC or with label D, E or F, but under an adjusted formula involving a correction factor. In Brussels, a comparable arrangement has applied since 14 October 2023 to homes with an EPB certificate of E, F or G. In Wallonia the restriction ended on 31 October 2023 and the ordinary formula applies again. In the German-speaking Community the measure expired on 31 December 2023.
Since the sixth state reform of 1 July 2014, tenancy law has been regionalised. Brussels introduced its Housing Code on 1 January 2018, Wallonia its Residential Tenancy Decree on 1 September 2018, and Flanders its own on 1 January 2019. Where those texts do not regulate an aspect, federal tenancy law continues to apply. In practice this means you need to know, for every lease, which Region the property is in and which rules were in force at the time.
Our free rent calculator applies exactly the same formula and the same official Statbel index figures. The difference lies in what you have to establish yourself. You enter your base rent, the start date, the signing date, your Region and your energy certificate; we automatically determine which initial index applies, which index figure matches your anniversary, and whether a correction factor is involved. You receive the calculation set out in full, so you can verify it or show it to your tenant.
A rent calculator gives you an amount, nothing more. The indexation itself only takes effect once you notify your tenant in writing. Without that request the old rent continues to apply, even when every condition is met. Moreover, your request only has retroactive effect for three months: whatever you forget is permanently lost. Anyone who has to keep track of this every year will eventually forget. That is exactly what our subscription is for, handling the calculation and the letter automatically every year.
Enter your base rent, start date and region and see straight away what you may charge this year. Based on the official health index, with the Flemish EPC correction applied automatically.
Go to the free calculator →Submit your contract and never miss an indexation.