Illegal construction in Spain: how to verify your property and what you need to know about the AFO

Illegal construction in Spain is one of the most significant risks foreign buyers face when purchasing property. From unlicensed swimming pools and enclosed terraces to homes built on rural land without planning permission, these irregularities can lead to fines, inability to connect utilities, or demolition orders. This guide covers the most common types of irregularities, how to verify a property’s urban planning status, what the AFO certificate is, and what to do if problems are found. At Ábaco Advisers, our independent legal team helps foreign buyers carry out thorough urban planning due diligence — in their own language and with no ties to estate agents or sellers.

What types of illegal construction are common in Spain?

The most frequent building irregularities involve swimming pools, enclosed terraces, extensions, and structures built on rural or protected land without proper planning permission from the local Town Hall (Ayuntamiento).

Spanish building law distinguishes between two categories of works requiring a licence or a Responsible Declaration (Declaración responsable de Obra)::

• Obra menor (minor works): installing a new kitchen, replacing windows, re-tiling, or fitting an awning. These require a licence from the Town Hall’s urban planning department.
• Obra mayor (major works): swimming pools, conservatories, extensions, additional floors, or structural changes. Even installing solar panels or paving a patio requires permission.

Properties built during Spain’s construction boom between 1995 and 2009 are particularly problematic. During this period, large numbers of homes were constructed on rustic land (suelo no urbanizable) without proper construction licences, especially in provinces like Almería, Málaga, and Alicante. According to data cited in Decreto-Ley 3/2019 from the Junta de Andalucía, out of approximately 500,000 buildings on non-developable land in Andalusia, around 300,000 were irregular.

Another common issue is the discrepancy between what exists physically and what appears in official records. A property may have extra rooms, a garage, or an enclosed terrace that don’t appear in the Cadastre (Catastro) or the Land Registry (Registro de la Propiedad). These mismatches are a red flag during due diligence and can cause serious complications for buyers who proceed without checking.

How can you verify the urban planning situation of a property in Spain?

You can check a property’s legal status by requesting a nota simple from the Land Registry, cross-referencing with the Cadastre, and obtaining an urban planning compliance certificate from the local Town Hall. This verification process is the single most important step a foreign buyer can take.

• Step 1 — Land Registry (nota simple). This document confirms who legally owns the property and reveals any outstanding debts, mortgages, or legal charges. It can be obtained from the Colegio de Registradores website for approximately €10. For more detail on how the Land Registry works, see our guide on the Spanish Land Registry. However, the nota simple only covers registered information — it won’t reveal building irregularities.
  
• Step 2 — Cadastre (Catastro) check. The Cadastre is the official property database maintained by the Spanish tax authorities. Compare the physical property, using aerial images and cross-referencing information with other administrations, with the registered description. Discrepancies between the Catastro and the Land Registry often indicate illegal construction that was never declared.
  
• Step 3 — Town Hall (Ayuntamiento) verification. This is the critical step most buyers skip. At the Town Hall’s urban planning department, request the building licence (Licencia de Obra), the first occupation licence (Licencia de Primera Ocupación), and a certificado de no infracción urbanística confirming there are no recorded urban planning infractions against the property.
  
• Step 4 — Independent architect survey. Commission a qualified Spanish architect to physically inspect the property and verify that what’s built matches the approved plans. This is especially important for rural properties where modifications may have been made over decades without documentation.
  

All of these checks should be completed before you sign a deposit contract or arras agreement. Your conveyancing lawyer should coordinate this entire process on your behalf.

What is the AFO certificate in Spain and when do you need one?

The AFO (Asimilado Fuera de Ordenación) is an administrative certificate issued by the local Town Hall that recognises the status of an irregular building. It was initially established in Andalusia through Decreto 2/2012, subsequently through Decreto-Ley 3/2019, and is now regulated under Ley 7/2021 (LISTA), Article 173 onwards, with detailed procedural rules in Articles 404-410 of Decreto 550/2022 (Reglamento LISTA).

It is essential to understand what an AFO does and does not do. The AFO does not legalise the building. It recognises that the enforcement period has expired and that the building meets minimum habitability conditions. This allows the owner to access basic utilities, register the property in the Land Registry, and potentially obtain a mortgage.

For the AFO to be granted, the building must meet several requirements under Article 173 of the LISTA:

• The construction must be finished.
• The enforcement period must have expired (six years from completion under Article 153.1 of the LISTA).
• There must be no active disciplinary or judicial proceedings against the property.
• The building must meet minimum conditions of safety and habitability.
• The building must not be on land affected by natural risks unless those risks have been mitigated.

The cost of obtaining an AFO varies significantly by municipality. Expect to pay for an architect’s report, Town Hall taxes, and checks on utilities and sanitation. Estimates range from €3,000 to €20,000. Processing times also vary — from a few months to over a year in some municipalities.

What is the difference between ‘legalisable’ and ‘outside permanent zoning’?

A legalisable property can still obtain full planning permission because the construction complies with current regulations. A property classified as fuera de ordenación cannot be fully legalised but may be tolerated through the AFO process.

A legalisable construction complies with applicable planning rules but was built without applying for a licence. The owner can apply retroactively, regularising the property fully.

The situation of fuera de ordenación is different. Under Article 173 of the Ley 7/2021 (LISTA), this covers buildings that breach current planning rules and cannot be brought into compliance. The AFO effectively “freezes” the property — the owner can maintain it but not expand it.

A third category carries the greatest risk: properties on protected land (suelo rústico de especial protección), including coastal zones, environmental protection areas (Red Natura 2000), and heritage sites. Under Article 153.2 of the LISTA, enforcement actions on certain specially protected land are not subject to the standard six-year limit, and demolition remains a real possibility regardless of age.

What should you do if you discover illegal construction on a property you want to buy?

If your due diligence reveals building irregularities, don’t panic — but don’t ignore them either. The key is to assess whether the situation can be regularised and negotiate accordingly before committing.

• Option 1 — Negotiate with the seller. The seller can obtain the AFO or retrospective licences before completion, or both parties may agree to reduce the purchase price. Costs are often shared on a 50/50 basis.
  
• Option 2 — Retain funds at completion. Your lawyer can retain a portion of the sale price in escrow to cover regularisation expenses, protecting the buyer while the transaction proceeds.
  
• Option 3 — Walk away. If the property sits on protected land or there are active disciplinary proceedings, the safest option may be to withdraw. Your arras contract should include suspensive conditions allowing deposit recovery.
  

The difference between buying with and without professional advice is stark. A couple who purchased without independent due diligence discovered an unlicensed extension and unpaid debts — costing over €35,000 to resolve. A family who engaged an independent lawyer completed their purchase safely for €3,000–4,000 in legal fees.

This is why Ábaco Advisers maintains strict independence from estate agents and sellers. For more information about the cost of buying property in Spain, including legal fees and external costs, visit our blog.

Key takeaways

Illegal construction in Spain is a widespread issue, particularly in coastal and rural areas popular with foreign buyers. Verifying a property’s urban planning status at the Town Hall is the most important step you can take — and the one most commonly skipped. With Spanish property prices continuing to rise, demand from international buyers is strong, making thorough due diligence more important than ever. The AFO certificate provides a pathway to regularise irregular properties in Andalusia, but it does not fully legalise them. If problems are found, practical solutions exist, but they require professional guidance.

If you are considering buying property in Spain and want to ensure the urban planning situation is thoroughly verified, contact Ábaco Advisers. We will be happy to offer you a free consultation in the language of your choice.

Frequently asked questions

Can a property with illegal construction in Spain be demolished?

Demolitions occur but are relatively rare for older properties. Under Andalusia’s Ley 7/2021 (LISTA, Article 153.1), enforcement measures must be adopted within six years of completion. Once this period passes without action, the property is generally exempt. However, properties on specially protected land may face enforcement without any time limit.

Do I need an AFO certificate to buy a rural property in Spain?

You do not legally need an AFO to complete a purchase, as Spanish law permits the sale of properties regardless of their planning status. However, without an AFO, you may face serious practical difficulties: inability to connect mains water or electricity, rejection of mortgage applications, and significant obstacles when you eventually want to resell.

How long does it take to obtain an AFO certificate?

Processing times vary enormously depending on the municipality. Some Town Halls resolve applications within six to nine months, while others take over a year. The process requires an architect’s report, various certifications, payment of local taxes, and inspection by the Town Hall’s planning department.

Is the AFO certificate available in all regions of Spain?

The AFO as a specific legal mechanism was established in Andalusia through Decreto 2/2012, later Decreto-Ley 3/2019, and now consolidated under Ley 7/2021 (LISTA). Other autonomous communities have their own urban planning legislation with different terminology and requirements. Always consult a lawyer familiar with the specific regulations in your region.