Your landlord raising the rent after a year? That will be because of rent indexing! Under the right conditions, it’s allowed. Find out how the rent indexation system works by region here.
1. Rent indexing: what is it?
The rent index(ering) or rent indexation determines the annual adjustment to the rent of a house or apartment. The index is a number that indicates the rate at which the rent increases. The index is calculated based on the health index. This applies to the Flemish, Brussels Capital and Walloon Regions. So does this mean that your landlord can adjust the agreed rent just like that? The answer: yes, as long as it is done under the right conditions. Note: Rent indexation in Flanders depends on the property’s EPC label since Oct. 1, 2023. Read all about it below.
2. As a landlord, when can you index?
You can legally adjust the rent once a year, based on the officially calculated index. This is at the earliest on the anniversary date of the lease. The landlord is not obliged to increase the rent. This is a free choice. If your lease states that the rent will not be indexed, it may not even happen. But if you don’t index rent one year, but you do the following year, it is completely legal. To avoid surprises, it’s best that the tenant and landlord communicate well about this (at the start of the lease).
2.1. Wat als de verhuurder te laat indexeert?
If you as a landlord forget to index the rent around the statute of limitations of the contract, you can still index it and report it within 3 months. You must then calculate the indexation on the month in which you should have reported the indexation. In addition, you may claim at most the indexation amount of the past 3 months. This is the same for the Flemish, Brussels and Walloon Regions.
3. Calculating rent indexation
3.1. Formule
The formula for indexing rents is the same for Flanders, Brussels and Wallonia:
( base rent x new health index ) / old health index
In which:
- Base rent: the rent in the original lease. Excludes any charges.
- New health index: the health index of the month before the anniversary date of the contract.
- Old health index: the health index of the month before when it was signed.
Note: Each region has implemented a separate correction factor as of October 2022. Please keep this in mind while indexing. View the rules by region under the following title.
Sample formula if you want to index on rent in January 2025:
New rent (January 2025) = Base rent (January 2024) x ( Health Index December 2024 / Health Index December 2023 )
Suppose (Note: these are fictitious figures):
- Basic rent: 1,000 euros
- Health index December 2024: 133.33
- Health index December 2023: 129.53
Then the calculation is as follows:
- New rent 2025 = 1,000 euros x (133.33 ÷ 129.53)
- New rent 2025 = 1,000 euros x 1.0293
- New rent 2025 = 1,029.34 euros
In this example, the rent is indexed to 1,029.34 euros per month from January 2025.
You can find the actual health index via this link on StatBel’s page. Or save yourself the math and use the Belgian government’s official rent calculator via this link.
4. Mandatory correction factor Flemish Region
4.1. Nieuwe correctiefactor o.b.v. EPC-score
From Oct. 1, 2023, landlords may index the rent in Flanders, regardless of the energy score. But double indexing is out of the question! The formula for indexing rents in Flanders with correction factor for houses without EPC or with EPC label D, E and F:
( base rent x new health index ) / old health index x correction factor
Find which correction factor to apply via this link to Vlaanderen.be. This depends on your EPC score and the anniversary date of your lease. For properties with EPC label A+, A, B or C, no correction factor applies. Note: The landlord must continue to apply the correction factor with every rent indexation, including in the years after 2023. The correction factor expires only if the landlord submits a better EPC or if a new lease starts.
4.2. Oude correctiefactor o.b.v. EPC-score
From Oct. 1, 2022, to Sept. 30, 2023, these rules applied, according to the Flemish government:
- Homes with EPC score A+, A, B and C: may be indexed as normal.
- Houses with EPC score D: may be indexed up to a maximum of 50%.
- Homes with EPC scores E, F and G: may not be indexed.
- Homes without an EPC score: may not be indexed.
5. Mandatory correction factor Brussels Capital Region.
5.1. Nieuwe correctiefactor o.b.v. EPC-score
From Oct. 14, 2023, landlords may index the rent in the Brussels Capital Region, regardless of the energy score. But double indexing is out of the question! The formula for indexing rents with correction factor for homes without EPC or with EPC label D, E and F:
( base rent x new health index ) / old health index x correction factor
Find what correction factor you should apply via this link to housing.brussels. It depends on your EPC score and the anniversary date of your lease. For properties with EPC label A+, A, B, C or D, no correction factor applies.
5.2. Oude correctiefactor o.b.v. EPC-score
From Oct. 14, 2022, to Oct. 13, 2023, these rules applied, according to the Brussels government:
- Homes with EPC score A+, A, B, C and D: may be indexed as normal.
- Homes with EPC score E: may be indexed up to a maximum of 50%.
- Homes with EPC scores F and G: may not be indexed.
- Homes without an EPC score: may not be indexed.
6. Mandatory correction factor Walloon Region.
6.1. Nieuwe correctiefactor o.b.v. EPC-score
As of Nov. 1, 2023, these rules will apply to the Walloon Region.
6.2. Oude correctiefactor o.b.v. EPC-score
From Nov. 1, 2022, to Oct. 31, 2023, these rules applied, according to the Walloon government:
- Homes with EPC score A+, A, B and C: may be indexed as normal.
- Homes with EPC score D: may be indexed up to a maximum of 75%.
- Homes with EPC score E: may be indexed up to a maximum of 50%.
- Homes with EPC scores F and G: may not be indexed.
- Homes without an EPC score: may not be indexed.
7. How can you index rent?
Rent indexation does not happen automatically. Do you want to index? Then calculate the new price yourself as above or using the official calculator (also take into account the correction factor). Communicate the rent increase:
- In writing via a registered letter to the tenant. The rent increase is only allowed if the tenant officially knows about it (and you can prove it).
- On the home’s anniversary date.
As a landlord, you have three months to notify the tenant from the time you can recalculate the rent. Since you can only make that calculation from the moment a full year has passed, rent indexation works retroactively. So, for example, the tenant may receive a letter in April, even if the start of the lease fell on March 1. The tenant will then have to pay the increased rent for both March and April as well as for the coming months. For example, if your lease starts on March 1, but your landlord chooses not to notify you until November that he wants to index the rent, you will only pay increased rent for November, October and September. This is because only those three months are covered by the statutory retroactive period.
8. What about rent indexing if the health index drops?
As a tenant, you also have the right to demand an adjusted rent when there is a negative index and it is in your favor – a lower rent! By registered letter, you can ask the landlord to adjust the rent to the index and thus lower it in case of falling inflation. In reality, this will not happen very quickly, but at least you will know that is your right.
Sources: Immoweb, Testaankoop, Flanders, Flanders
Would you like to cite this article as a source? Then use:
Biets, R. (2024, Nov. 27). Rent indexation according to legislation. Apartment.be. Consulted on (date XX/XX/202X), from https://www.appartement.be/hoe-werkt-huurindexering/
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