How to verify a rent indexation

Quick answer

Take the base rent from the original lease, find the starting health index (month before signing) and the new index (month before anniversary) on Statbel. Apply the formula: Base rent x (New index / Starting index). Compare with the amount your landlord requested.

To verify an indexation, you need three pieces of information:

  1. The base rent stated in the original lease agreement
  2. The starting health index: published by Statbel for the month preceding the lease signing
  3. The new health index: for the month preceding the anniversary of the lease entry into force

Apply the indexation formula and compare the result with the amount the landlord is requesting.

Common errors to look for

When verifying, check for these frequent mistakes:

  • Wrong base rent: the landlord may have used last year’s indexed rent instead of the original base rent
  • Wrong index period: using the wrong month for the starting or new index
  • Wrong index type: using the consumer price index instead of the health index
  • Rounding errors: the result should be rounded to the nearest cent
  • EPC non-compliance: the property may be subject to indexation restrictions based on its energy label
Practical tip

Use our indexation calculator to instantly verify the calculation. Simply enter your lease details and the tool will show the correct indexed rent based on the latest official indices.

What to do if the indexation is incorrect

If your verification shows a different result from the landlord’s calculation:

  1. Contact the landlord in writing, explaining the error and providing your own calculation
  2. Attach supporting documents: reference to the base rent in the lease, the correct indices from Statbel
  3. Request correction: ask for the correct amount going forward and reimbursement of any overpayment
  4. If the landlord refuses: send a registered letter (recommande) reiterating your calculation
  5. Last resort: file a complaint with the Justice of the Peace (juge de paix)

Regional specifics

Brussels-Capital Region

In Brussels, also verify that the property meets EPC requirements under the Ordinance of 27 July 2017. Properties with EPC labels E, F or G face indexation restrictions.

Wallonia

Under the Decree of 15 March 2018, similar EPC restrictions apply. Verify the property’s energy label before accepting the indexation.

Flanders

Under the Flemish Housing Rental Decree of 9 November 2018, only EPC labels E and F trigger indexation limitations.

Legal basis

Article 1728bis of the Belgian Civil Code. The tenant has the right to verify any indexation calculation and contest it if incorrect.

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