Rent Adjustment: CPI, Reference Index and Caps

The legal framework for rent adjustments under the LAU

Article 18 of the Urban Leases Act sets out the general principle regarding how and when rent prices may be reviewed. For a rent adjustment to be carried out validly, a number of essential formal requirements must be met:

• Express agreement between the parties: If the tenancy agreement does not include a specific clause providing for rent reviews, the rent cannot be adjusted during the lifetime of the contract. The absence of an express agreement implies a freeze on the initial agreed amount.
• Annual frequency: Rent reviews can only take place when the contract completes a full year in force. It is not legal to apply cumulative increases or reviews for periods shorter than twelve months.
• Written notification: The landlord must communicate the adjustment to the tenant in writing, explicitly stating the percentage variation applied and attaching the certificate from the INE or the corresponding informational note.
• Effective from the following month: The new adjusted rent will become payable from the month following that in which the interested party notifies the other party of the review in writing.

It is important to note that adjustments are not retroactive. If the landlord does not notify the review in the month the contract reaches its anniversary, they may do so in subsequent months, but the increase will only start applying from the month following notification, with no possibility of claiming back uncollected arrears for previous months.

From CPI adjustments to new legal caps

Traditionally, the standard reference used for rent adjustments has been the percentage variation of the Consumer Price Index (CPI) published by the INE. However, extraordinary measures approved in recent financial years have progressively limited this direct link to curb the impact of inflation on the housing market.

1. The Consumer Price Index (CPI)

In contracts prior to recent legislative changes, the general CPI set the upper limit for annual rent increases. To perform the calculation, the reference used was the latest index published as of the contract adjustment date, which usually corresponds to the figure published two months prior to the anniversary date.

2. Extraordinary temporary caps

In order to mitigate high inflation rates, legislation introduced mandatory temporary limits that decoupled adjustments from the general CPI:

• 2% cap: Applicable during the financial years in which emergency economic measures were enacted to prevent disproportionate rises driven by energy and food CPI.
• 3% cap: Established for rent reviews taking effect during 2024.

In contracts where the landlord is a large property holder (owner of more than 10 urban properties or a residential built area exceeding 1,500 m², or as determined by the autonomous community), the maximum increase cannot exceed these legal percentages, regardless of whether the actual CPI is higher.

3. The INE's new reference index for 2025

The Law on the Right to Housing has tasked the INE with creating a new reference index for rent adjustments, designed to prevent disproportionate increases in monthly payments. This index permanently replaces the CPI as an automatic ceiling for annual reviews, providing a more stable metric tailored to the real estate sector.

Specific provisions in the Comunidad de Madrid and protected housing

When applying a rent adjustment, it is necessary to distinguish the property type and its protection regime. In the specific case of the Comunidad de Madrid, properties subject to any public protection housing regime (VPO, VPPB, VPPL) must adjust rent to the maximum price tables approved by the regional authority.

If the property is undergoing a disqualification process in the Comunidad de Madrid or has reached the end of its legal protection period, the lease will become fully governed by the general regime of the Urban Leases Act. As long as it retains protected status, the updated rent cannot under any circumstances exceed the legal limit per usable square metre set by regional Madrid regulations for that public housing module.

How to calculate rent adjustments step by step

To formalise a rent adjustment correctly without incurring errors that could invalidate the notification, the following procedure is recommended:

1. Check the agreement: Verify that an explicit rent review clause exists and check the exact date of signing or entry into force.
2. Consult the applicable index: Identify the official figure published by the INE corresponding to the month agreed in the contract (or the maximum cap set by law for that period).
3. Apply the mathematical formula: Multiply the current rent by the variation in the reference index or legal cap and add or subtract the result from the amount previously paid.
4. Draft written communication: Issue a written notice to the tenant reflecting the percentage applied, the itemised calculation, and the exact date from which the new rent will be charged.
5. Send the notification: Use a verifiable method ensuring receipt by the tenant, such as a burofax with text certification and proof of delivery, or a notice signed in person.

Asset management and alternatives in the face of regulatory uncertainty

The constant evolution of regulations regarding rent adjustments, combined with caps in stressed housing market areas and changes in property taxation, poses significant challenges for owners seeking to protect the value of their assets and secure stable long-term income.

Managing tenancies requires continuous legal knowledge to comply with formal notices on time and avoid legal disputes with tenants. Any flaw in the written communication of the rent review can prevent the application of the corresponding increase, resulting in a loss of annual yield for the landlord.

For property owners who prefer to avoid the management burden associated with annual reviews, CPI fluctuations, and the risk of default in traditional letting, innovative wealth management solutions are available in the real estate market.

At Sky Real Estate, we assist property owners in making strategic asset management decisions. Our legal division has been recognised with prestigious awards such as the Sky Law European Legal Awards 2023-2025, underlining the strength of our operations. Furthermore, we operate with maximum institutional transparency, being registered in the Real Estate Credit Intermediaries register of the Banco de España under code ICI D-286.

If you require immediate liquidity without relinquishing the use or yield of your property and free from the constraints of traditional rental management, you can explore tailored arrangements designed to optimise your financial capital with total legal peace of mind.

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