How Is the Cadastral Income Calculated for Your Property?

Anyone who owns or wants to buy property in Belgium quickly runs into the same question: how is cadastral income calculated and what does that mean in practice for my finances? The cadastral income (CI) is a key concept in the Belgian tax system. It largely determines how much property withholding tax you pay and plays a role in how your property is assessed, both by banks and by buyers and investors. Yet for many owners it remains an abstract, almost mysterious figure. This article explains step by step how the CI is established in practice and what you, as a (future) owner, need to do with it.

What exactly is the cadastral income (CI)?

The cadastral income is not actual rent that you receive, but a fictitious annual income that the government assigns to every piece of real estate in Belgium. It is an estimate of what your property would yield net per year if you were to rent it out, expressed in euros per year. This fictitious rental value then serves as the basis for various taxes - primarily the property withholding tax at regional level - and for certain calculations in personal income tax.

An important point is that this estimate is historically pegged to a single reference date: 1 January 1975. The tax authorities therefore do not look at current market prices, but at what your property could have yielded in 1975 as a rental property. To bring the figure at least roughly in line with today's economic reality, the CI has since been indexed every year using an official indexation coefficient. As a result, the CI broadly follows the evolution of consumer prices, without a full revaluation of all properties taking place.

How is cadastral income calculated in theory?

The question