Rent Indexation: How to Verify Your Landlord's Calculation
The Indexation Formula
The formula is the same in all three regions:
New rent = Base rent × New health index / Starting index
| Element | Meaning | Where to Find It |
|---|---|---|
| Base rent | The rent stated in the lease at signing | Your lease contract |
| New index | Health index of the month preceding the lease anniversary | Statbel (published monthly) |
| Starting index | Health index of the month preceding the lease signing | Statbel (archives) |
Verification Example
Your lease was signed on 1 June 2022 with a rent of €850.
- Starting index (May 2022): 123.74
- New index (May 2024): 130.12
Correct calculation: 850 × 130.12 / 123.74 = €893.82
If your landlord asks for €920, the calculation is incorrect.
Conditions for a Valid Indexation
Your landlord can only index if all these conditions are met:
| Condition | Verification |
|---|---|
| The lease contains an indexation clause | Re-read your lease (present by default) |
| The lease is registered | Check on MyMinfin |
| The request is made in writing | Email, letter, or registered mail |
| Maximum once per year | On the anniversary date of the lease |
| The EPC certificate is valid | According to regional restrictions |
EPC Restrictions by Region (since 2023)
BBrussels
For leases that entered into force from 14 October 2022 onwards: full indexation is allowed regardless of the EPC rating. No restriction.
For leases that entered into force before 14 October 2022 with an EPC E, F or G: a correction factor applies. The landlord cannot recover the lost indexation during the freeze period. Verify the calculation with the official calculator.
Official calculator: Loyers.brussels — enter your data and compare with what your landlord is asking.
WWallonia
Since 1 November 2023, the EPC limitation has been lifted. Full indexation (100%) is allowed for all EPC ratings (A to G).
For leases whose anniversary fell between 1 November 2022 and 31 October 2023, a limitation applied (75% for EPC D, 50% for EPC E, 0% for EPC F/G). The "adapted" rent from that period serves as the base for future indexations.
VFlanders
For leases that entered into force from 1 October 2022 onwards: full indexation without restriction, regardless of EPC.
For leases that entered into force before 1 October 2022 with an EPC D, E or F: a correction factor applies. The calculation uses a corrected index that prevents recovery of the lost indexation during the freeze period.
Flanders specificity: the starting index is the one from the month preceding the entry into force of the lease (not the signing date).
Info: Woninghuur Vlaanderen
How to Contest an Incorrect Indexation
Step 1: Verify the Calculation Yourself
- Find the base rent in your original lease
- Identify the anniversary date of your lease
- Look up the health indices on Statbel
- Apply the formula
- Check the EPC restrictions for your region
- Compare with the amount requested by your landlord
Step 2: Report the Error in Writing
Send a letter (registered preferably) to your landlord with:
- Your detailed calculation (formula + indices used)
- The correct amount according to you
- The request for correction
- If applicable: the EPC restriction that applies
Step 3: Pay the Correct Amount
You can pay the correctly calculated indexed rent and refuse the surplus. Keep a written record of your contestation.
Step 4: Refer to the Justice of the Peace
If the landlord insists on an incorrect amount, you can refer to the justice of the peace (free conciliation, then proceedings if necessary).
Cases Where Indexation Is Prohibited
| Situation | Consequence |
|---|---|
| Unregistered lease | No indexation possible |
| No indexation clause in the lease | No indexation possible |
| Non-written request | Indexation is not due |
| Retroactive request (> 3 months) | Only the last 3 months are due |
Retroactive Effect: What You Need to Know
| Region | Maximum Retroactivity |
|---|---|
| Brussels | 3 months back |
| Wallonia | 3 months back |
| Flanders | 3 months back |
If your landlord asks you to pay an indexation for the last 12 months when they never requested it, you only owe a maximum of the last 3 months.
Common Landlord Mistakes
| Mistake | Why It's Wrong |
|---|---|
| Using the current rent as the base | The base is always the rent from the original lease |
| Using the CPI instead of the health index | The health index excludes alcohol, tobacco, fuels |
| Indexing without a registered lease | No registration = no indexation |
| Indexing an EPC F in Brussels without correction factor | The correction factor must be applied (temporary restrictions lifted, but correction mandatory) |
| Requesting a 2-year catch-up | Maximum 3 months retroactivity |
| Indexing twice in the same year | Maximum once per year |
Verification Tools
| Tool | Use | Link |
|---|---|---|
| Loyers.brussels | Official calculator (all regions) | loyers.brussels |
| MyMinfin | Check lease registration | eservices.minfin.fgov.be |
| Statbel | Consult health indices | statbel.fgov.be |
Official Links
- Loyers.brussels — Official indexation calculator
- MyMinfin — Lease Registration — Check if your lease is registered
- Brussels Housing — Indexation — Brussels rules
- Wallonia — Renting a property — Walloon framework
- Woninghuur Vlaanderen — Flemish framework
- Belgium.be — Rental — Federal legal framework
Selectio automatically calculates your indexation and alerts you if the amount requested by your landlord does not match the legal formula. Learn more →