In Belgium, rent is adjusted each year based on the health index. Here we explain the exact formula, with concrete examples.
Rent indexation in Belgium follows a fixed legal formula: new rent = base rent × new health index ÷ base index. The base rent is the amount in the original lease, excluding charges. The base index is the health index of the month before the lease was signed. The new index is the one of the month before the lease anniversary.
The health index is an official Belgian index calculated monthly by Statbel. It derives from the consumer price index but excludes tobacco, alcohol, petrol and diesel. It is used specifically for rent indexation, so the adjustment reflects the real cost of living.
Suppose a lease signed in January 2021 with a base rent of €800. The health index for December 2020 was 109.57. In December 2024 it was 128.42. The calculation: €800 × 128.42 ÷ 109.57 = €937.42. From January 2025 your tenant therefore pays €937.42 per month — €1,649 more per year.
You may index on the anniversary of the lease taking effect. Note: this is not the signing date, but the date the tenant actually took possession. Indexation is not automatic — you must request it or have it calculated.
In Belgium, rent is adjusted each year based on the health index.
Forgot to index? In Flanders and Wallonia you can claim up to three months retroactively. Indexing on time each year therefore matters. With our platform you never miss a deadline: we track every anniversary and send the letter for you.
In Flanders a temporary EPC-based limitation applied from October 2022 to October 2023. It has ended: indexation is allowed again for every label. However, for residential leases that took effect before 1 October 2022 with label D, E, F or no valid EPC, a correction factor still applies. We calculate it automatically.
The calculation requires looking up the correct index figures, applying the formula properly and knowing the regional rules. A single mistake can lead to a dispute with your tenant or even legal trouble. Our platform automates the whole process: we calculate, draft the letter and send it to your tenant.
Our service costs €30 per year per lease. On a rent of €800 with 3% indexation that already yields €288 extra per year — nearly ten times the cost of the service.
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.