A 1,000-euro annual rent? Impossible.

There are large town houses in fancy neighbourhoods that have a CI of only 450 euros. Meanwhile, there are small apartments in dilapidated areas that have a 1,300-euro CI. This means that the owner of the small apartment has to pay more property tax than the owner of the fancy town house.

"Normally, the cadastral income should represent the total net value of the annual rent", explains Tax Law Professor Michel Maus. "But if we look at current CIs, it's clear as day that this isn't the case. I think that, right now, the average house has a CI of around 1,000 euros. We all know it's completely impossible to rent a house for only 1,000 euros a year."

The tax man should re-evaluate CIs every ten years. Unfortunately, this hasn't happened since 1975. "So what we have now is a gross underestimation of the average CI. This is good for citizens of course, they have to pay less property taxes in most cases. But it's bad news for the government, which is falling short of a lot of tax income.

The government thinks that, unfortunately for them, it is impossible to re-evaluate CIs every ten years. "That is the political argument they use to explain the prolonged disregard of the issue. Of course it's a difficult task for the tax man to go out and assess every piece of real estate. Administratively speaking, this is a tough job to carry out, but unfortunately, it is legally mandatory.”