What is the base index of your lease contract?

That time of year has come again: you may index the rent on your rented property. You have the formula for calculating rent indexation at hand, your letter template for indexation is ready… but then you get stuck when you need to fill in the actual figures.

Rent indexation formula

We will first briefly recap the calculation of rent indexation in Belgium. Then we explain where you can find the different figures for a lease contract. The formula is as follows:

Base rent x new index (= health index) / base index

Where do you find the base rent?

The first figure, the base rent, is straightforward. For this you take the rent amount set out in the lease contract. You always use the same amount here. When the base rent is, for example, €800 and was already indexed to €825 last year, you still perform this year's calculation based on the original €800.

Where do you find the new health index?

Next we look at the new index. That figure is based on the current health index and can be found on the Statbel website. When indexing rent, you always use the index figure for the month preceding the month in which you index. If you index the rent on 1 July, for example, you take the figure for June. In 2022 that figure was 121.02.

Finally, pay close attention to which part of the table you read. The health index is sometimes reset to the base figure of 100. That happened in 1996, 2004 and 2013. If your lease contract was drawn up between 1996 and 2004, you take the first part of the table. For lease contracts between 2004 and 2013, you take the second part. Finally, for lease contracts drawn up after 2013, you look at the last part.

Where do you find the base index?

Lastly, we still need the base index. The base index of your lease contract is the health index figure for the month before the contract takes effect. This last part is very important, especially for contracts that only actually start months after signing. When the lease contract was signed on 15 February 2021, for example, but only takes effect on 1 July 2021, you take the index figure for June 2021. That figure was 111.31 at the time.

Let's fill in this complete formula: 800 x 121.02 / 111.31 = 869.79. The only figure you therefore need to look up and update annually to calculate rent indexation is the new health index.

Calculate rent indexation automatically

Would you like to calculate rent indexation automatically so you don't waste time on it? SNDQ can help you with that. By entering all the lease contract information once, our software can calculate the indexation for you. You can also set the rent to be indexed automatically every year. Communication to the tenant is also fully automated, so you never miss out on income through forgetfulness.

Does that sound interesting? Be sure to explore the other features of SNDQ on the website and contact us for more information.