Rent Indexation Calculator Belgium — Free Tool
What is Rent Indexation?
Rent indexation is the annual adjustment of the rent to the cost of living. In Belgium, this is legally regulated through Article 1728bis of the Civil Code. The indexation is based on the health index (gezondheidsindex / indice santé), a variant of the Consumer Price Index that excludes certain products like tobacco, alcohol, petrol, and diesel.
Thanks to indexation, the rent evolves with inflation without requiring a new lease agreement. However, the landlord must notify the tenant in writing of the indexation. The adjustment does not happen automatically.
How is Rent Indexed in Belgium?
The legal formula for rent indexation in Belgium is:
New Rent = Base Rent × (Current Health Index / Base Health Index)
Where:
- Base Rent: the monthly rent as stated in the lease agreement at the start of the tenancy.
- Base Health Index: the health index (gezondheidsindex) from the month before the lease was signed.
- Current Health Index: the health index from the month before the anniversary of the lease start date.
Calculation Example:
- Base rent: €1,000/month
- Base health index (January 2022): 113.09
- Current health index (January 2026): 137.37
- Calculation: €1,000 × (137.37 / 113.09) = €1,214.70
- Increase: +21.47% over 4 years
When Can You Apply Indexation?
Rent indexation may be applied once per year, on the anniversary of the lease start date. Important rules:
- Indexation is not automatic — the landlord must request it in writing.
- Indexation can be requested retroactively, but only for a maximum of 3 months.
- If the lease contract explicitly excludes indexation, it may not be applied.
- Regional rules in Brussels and Wallonia may impose additional restrictions, for example for properties with a poor energy performance certificate (EPC).
Note: In the Brussels-Capital Region and Wallonia, there are restrictions on indexation for properties with a poor energy performance certificate (EPC). Always verify the applicable regional legislation.
Rent Indexation 2026
For 2026, the most recent health index values (base year 2013 = 100) are as follows:
| Month | Health Index |
|---|---|
| January 2026 | 137.37 |
| February 2026 | 138.06 |
| March 2026 | 137.78 |
Compared to 2025, the health index has increased by an average of 1.5–2%. This means tenants receiving an indexation in 2026 can expect a moderate increase. Inflation has decreased significantly compared to the peaks seen in 2022–2023.
For comparison: the health index rose by more than 10% in 2022, while the increase in 2025–2026 is around 1.5–2%. This translates into smaller rent increases for new indexations.
Health Index vs. Consumer Price Index (CPI)
The health index (gezondheidsindex) differs from the regular Consumer Price Index in that certain products are excluded: tobacco, alcohol, petrol, and diesel. This index was introduced in 1993 to prevent excise duty increases on these products from automatically affecting rents and social benefits.
The health index is published monthly by Statbel, the Belgian statistics office. The most commonly used series has base year 2013 (2013 = 100).