Belgian rent indexation 2026
Calculate the new legal rent after indexation, from the base rent, lease signature date and anniversary date. Based on the official Statbel health index.
Parameters
The anniversary month is automatically the same as the signature month, only the year changes.
Enter the base rent and both dates to see the indexed rent.
The legal formula, explained
Since 1994, rent indexation in Belgium has followed a single formula, set by the law of 23 April 2015: base rent × new index / starting index. No room for interpretation, the result is the same regardless of the tool used, as long as the right indices are applied.
1. The base rent
This is the rent excluding charges set when the lease was signed, never the last indexed rent from a previous year. Every subsequent indexation is calculated from this same original reference.
2. The starting index and the new index
The starting index is the health index of the month preceding the lease signature. The new index is the health index of the month preceding the anniversary of the lease taking effect, i.e. the date you're requesting this year's indexation. Both indices come from the same official series, published monthly by Statbel.
3. Once a year, on written request
Indexation is never automatic: it's up to the landlord to request it in writing, once a year at the earliest on the anniversary date. Without a request, the rent stays unchanged, but the landlord retains the right to claim the last three months of back-indexation if they forgot.
What this calculator does not cover
Between 1 November 2022 and 31 October 2023, a temporary measure capped indexation based on a property's EPC rating (from 100% for A-B-C ratings down to 0% for F-G) in Wallonia and Brussels, with effects that may still affect the base rent of some leases today. This calculator applies the general rule and does not model that specific case; if your anniversary date fell within that period, check your situation on your region's portal. Commercial leases follow separate rules, not covered here.
Frequently asked questions
How is rent indexation calculated in Belgium?
The legal formula is: base rent (excluding charges) × new index / starting index. The starting index is the health index of the month preceding the lease signature; the new index is the health index of the month preceding the anniversary date of the lease taking effect.
What is the health index?
It is the consumer price index with tobacco, alcoholic beverages and fuel (except LPG) removed. Belgium's FPS Economy (Statbel) publishes it monthly, around the 25th. This index, not the "smoothed health index" used for wages and pensions, is the one used for rent indexation, under the law of 23 April 2015.
When can rent be indexed?
Once a year, at the earliest on the anniversary of the lease taking effect, unless the contract states otherwise. Indexation is not automatic: the landlord must request it in writing (a letter, email or text message is enough, provided you keep proof).
What happens if the landlord forgets to index the rent?
They can still do it, but their right to back-indexation is limited to the three months preceding their request.
Does this calculator cover every lease?
It covers the general rule for a primary residence lease. It does not account for the temporary EPC-based indexation cap that applied in Wallonia and Brussels between 1 November 2022 and 31 October 2023 (whose effects may still impact the base rent of some leases today). It also does not cover commercial leases.
Why can't I index a lease signed before 2015?
The index table built into this tool covers 2015 to today, which is enough for nearly all active leases. For an older lease, use the official Statbel calculator, which covers the full history since 1994.
Does the lease need to be registered to index the rent?
Yes, since 1 September 2018, a primary residence lease must be registered for the rent to be indexed, whether the contract is new or was already running on that date.
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