The Standard for the Free Sector: 'Indexatieclausule'
An index-linked lease is the default and most common method for calculating the annual rent increase (huurverhoging) for properties in the free sector (vrije sector). The rental agreement will contain an indexatieclausule (indexation clause), which stipulates that the rent will be adjusted once per year based on the percentage change of a specific, objective economic index. This creates a predictable and transparent method for rent escalation, preventing the landlord from arbitrarily imposing a large increase. The tenant knows that the rent will rise, but the increase is tied to a verifiable, external metric.
The Consumer Price Index (CPI)
The index used is almost always the Consumer Price Index (Consumentenprijsindex - CPI), as published by the official Centraal Bureau voor de Statistiek (CBS), the Dutch national statistics office. The CPI is the official measure of inflation. The indexation clause will typically state that the rent will be increased annually by the CPI percentage from a specific month. For example, the rent might be adjusted on July 1st each year based on the CPI figure from the preceding January. The contract may also include an additional fixed percentage on top of the index, for example, 'CPI + 1%'.
The Overriding Legal Cap
It is crucial for tenants in the free sector to be aware that their indexation clause is subject to an overriding legal maximum. As of August 2025, a law is in effect that caps all free-sector rent increases at inflation (CPI) + 1%. This means that if your contract contains a clause that allows for a higher increase (e.g., 'CPI + 3%'), that clause is partially invalid. The landlord is only allowed to apply the legal maximum increase of CPI + 1%. This legislation provides a vital protection against the high inflation rates seen in recent years, preventing them from translating into extreme rent hikes.