The Catalan government is deploying artificial intelligence to create an updated map of vacant homes across Catalonia, a move aimed at increasing the availability of rental housing. The Generalitat, working with local councils, has commissioned the International Center for Numerical Methods in Engineering (CIMNE) in Lleida to develop the model, which will integrate data on water and electricity consumption, census records, and door-to-door surveys.

Currently, official figures estimate 417,652 vacant homes in Catalonia, a figure derived from electricity consumption data and published by Idescat via the INE population and housing census. However, the Generalitat acknowledges that this number is indicative, as declarations of vacancy by large property owners are voluntary and often outdated.

All of this was in a kind of no-man's-land, which meant the issue wasn't being tackled.

Jordi Mas Herrero, Director General of Housing, said the new AI-driven approach will provide accurate, municipality-level data starting next year. Until now, determining whether a flat was vacant required a physical inspection by an official. A legal change now allows councils to use data to declare a property unoccupied.

The initiative forms part of the Territorial Sectoral Housing Plan due to be finalised by the end of 2024. Rather than penalising owners, the Generalitat plans to incentivise the use of vacant homes through partnerships with municipalities, offering rehabilitation subsidies and tax reductions in exchange for below-market-rate rentals.

Municipal Action and Financial Measures

While the Generalitat has not issued any fines for vacant properties in the past three years, despite legal provisions allowing penalties for large landlords with unoccupied flats for over two years, some local councils have taken action. Thirteen municipalities, including Sitges, Rubí, and Vilafranca del Penedès, issued 230 surcharge notices in 2025, raising €106,026.43.

Under national and regional regulations, councils may apply an IBI (property tax) surcharge of up to 150% on homes owned by individuals or entities with four or more residential properties that remain continuously unoccupied for more than two years without justified cause. Justified reasons include temporary relocation, health needs, pending sale or rental, or ongoing renovation.

A separate tax on large property holders, those owning more than 15 vacant flats over 150m² unoccupied for two years, generated €7 million in 2024. Revenue from this tax funds the purchase of homes for social housing. By 2025, collections had dropped to €2.84 million, according to the Department of Economy, suggesting some previously vacant homes had been repurposed.

Local Incentive Models

  • Olesa de Montserrat used cross-referenced utility and registry data to identify 120 vacant flats between 2024 and 2025, and now offers tax incentives for owners who rent below market rate.
  • El Prat de Llobregat previously identified 180 vacant units and successfully attracted financial entities to lease them via tax bonuses and payment guarantees, though this flow has slowed as banks resume sales.

Despite these efforts, the Renters’ Union has criticised the lack of enforcement, stating: "The government is doing nothing to guarantee the right to housing." The organisation called for a properly resourced inspection force and stricter regulation of short-term lets.

The Council of Statutory Guarantees has also raised legal concerns about proposed housing legislation restricting property use, citing potential breaches of constitutional rights to property and enterprise. However, its opinion is non-binding, and the bill remains under parliamentary review.

Reported by 3cat.cat, ARA, Agustí Sala, democrata.es, Víctor Sanz Guerrero, 3CatInfo Barcelona.