Short answer: the Spanish Land Registry (Registro de la Propiedad) and the Cadastre (Catastro) are two distinct institutions with distinct purposes, and they do not have to agree. The Registry publishes who owns the property and what charges affect it; the Cadastre describes the property primarily for tax purposes. Neither of them, on its own, establishes that a construction is lawful in planning terms. When the square metres, the swimming pool or the buildings do not match, the first step is not to correct the paperwork: it is to establish which of the three realities — registered, cadastral and physical — is the correct one, and why they differ.
This is the most frequent issue in villa purchases on the Costa Blanca. The registry extract says 180 m²; the Cadastre says 214 m²; and on site there is also a swimming pool that appears in neither. From there, the two usual reactions are both wrong: either the problem is ignored because “the bank hasn’t said anything”, or the purchase is abandoned because “the house is illegal”. Neither conclusion holds without prior analysis.
Contents
- What each institution does and why discrepancies arise
- Vocabulary: ten terms that do not mean the same thing
- Fourteen specific situations and what each one means
- Three statements we hear every week — and that are wrong
- What documents must be requested
- Who should resolve the discrepancy: buyer or seller?
- Decision tree
- Frequently asked questions
- Legal sources
What each institution does and why discrepancies arise
The Land Registry is a register of rights. It publishes who holds title, what rights in rem exist over the property and what charges burden it. What is registered is presumed accurate and protected by the courts. But the Registry operates on application: it reflects only what someone has asked to be registered. If nobody declared the extension, the extension does not appear — and that absence says nothing about whether the works were lawful.
The Cadastre is an administrative register describing properties, under the Spanish Ministry of Finance, whose main purpose is fiscal: it underpins the IBI property tax and other levies. Article 3 of the consolidated Cadastral Law (Royal Legislative Decree 1/2004) provides that the cadastral description must reflect physical reality, and that the cadastral certificate is presumed accurate unless the contrary is proved. The practical consequence is twofold: the Cadastre tends to record what exists — whether declared by the owner or detected by the authority from aerial imagery — regardless of whether it has planning permission, because its function is to tax, not to authorise.
Physical reality is what you see when you visit the property. And it is the only one of the three that is not open to argument.
Discrepancies have readily identifiable origins: properties registered decades ago with imprecise literary descriptions, extensions built and never declared, works declared to the Cadastre but never registered — or the reverse, old measurements versus current georeferenced mapping, and poorly documented segregations and groupings. On the Costa Blanca there is a further local factor: decades of rapid construction in the 1970s and 1980s under far weaker documentary control than today’s.
Since Law 13/2015, which reformed both the Mortgage Law and the Cadastral Law, a coordination mechanism exists. When a property achieves the status of coordinated, article 10.5 of the Mortgage Law presumes that the registered graphic delimitation corresponds to reality. Most older properties are not yet coordinated.
Vocabulary: ten terms that do not mean the same thing
A large share of the mistakes in this area are vocabulary mistakes. It is worth fixing the distinctions first.
- Registry discrepancy: what the Registry states does not match physical reality. Corrected through articles 199, 201 or 202 of the Mortgage Law, depending on the case.
- Cadastral discrepancy: what the Cadastre states does not match reality. Corrected by the owner’s declaration of alteration (article 13) or by the discrepancy-correction procedure of article 18.
- Unregistered construction: the building exists but does not appear in the Registry. A problem of registry publicity, not necessarily of legality.
- Undeclared construction: the building was not notified to the Cadastre. A breach of a formal tax obligation, with possible penalty and back-assessment of IBI.
- Construction without a licence: built without the planning consent required. This is a legality problem, and it is independent of the previous two.
- Planning infringement: conduct that may give rise both to penalty proceedings and to proceedings for restoration of planning legality.
- Declaration of new construction: the deed that brings the building onto the Registry. For an ordinary completed building it requires the licence, a technical completion certificate and, where applicable, ten-year insurance (article 28.1 of Royal Legislative Decree 7/2015).
- Declaration of new construction by antiquity: the route under article 28.4 of the same text, for buildings against which restoration measures can no longer be taken. It requires proof of age and the absence of any registered note of pending enforcement proceedings.
- Outside planning (fuera de ordenación): the building is tolerated but does not conform to the current plan. This limits the works that may be carried out on it.
- Regularisation: a generic and ambiguous word. It may mean a cadastral update, a registry entry or a planning legalisation. These are not the same, and it is always worth specifying which is meant.
Fourteen specific situations and what each one means
1. The Registry shows fewer built square metres than the Cadastre
The most common case. It usually means the property was extended and the extension reached the Cadastre — by declaration or by official review — but never the Registry. The extension must be dated, the licence checked, and it must be established whether the restoration period has expired. Only then can the registration route be chosen.
2. The Registry shows more square metres than the Cadastre
Less frequent and often harmless: it may result from an undeclared partial demolition, from different measurement criteria (built versus usable area, how porches and terraces are counted) or from a historical error. It matters mainly for its tax effect and because the bank will value what actually exists.
3. Pool in the Cadastre but not in the Registry
Very common in villas in Alfaz del Pi, Altea and Benissa. Its presence in the Cadastre shows the tax authority knows about the pool and is taxing it; it does not show that it has a licence. The decisive check is at the town hall.
4. A pool that physically exists but appears in neither
The clearest warning sign: nobody has declared it anywhere. Check whether a building licence exists at the town hall and whether the restoration period has expired. If the pool is recent and unlicensed, the risk of enforcement is real and falls on whoever owns the property when the notice arrives.
5. Unregistered extension
Same analysis as case 1, with one relevant nuance: if the extension affects the structure or the built volume, the technical certificate will be more expensive and the bank may make financing conditional on prior registration.
6. Enclosed porch
Glazing a porch is major works where it creates countable built surface area. It is the case owners most underestimate, perceiving it as a domestic improvement. In an owners’ community it is also necessary to check whether the community resolution permitted it.
7. Garage
It must be established whether the garage is a separate registered property, an inseparable annex to the dwelling, or merely a share of use over a common element. The three arrangements have different consequences on transfer, and older deeds frequently confuse them.
8. Storeroom
Same analysis as the garage. A storeroom used for twenty years that is neither an annex nor a separate registered property may not form part of what you are buying.
9. Basement
Excavation after the original construction is major works. A basement may also raise habitability and buildability questions. Check whether it appears as built surface area in the Cadastre and under what use.
10. Guest house
The highest-risk case. A separate second building may constitute an increase in residential units not permitted by the plan, particularly on non-developable land. It is not comparable to an extension: it may be incapable of legalisation altogether. We also address this in our article on buying property on rustic land.
11. Differences in plot area
A specific regime applies here. Article 201.3 of the Mortgage Law allows area differences to be recorded without formal proceedings where they do not exceed 10% of the registered area and are evidenced by a descriptive and graphic cadastral certificate, or where they do not exceed 5% of the registered area. Above those thresholds the notarial procedure of article 201 is required, with neighbouring owners involved. Worth knowing: a 12% difference is not sorted out in an afternoon.
12. Differences in boundaries
More delicate than area differences, because they affect third parties. The route is the registry procedure of article 199 — incorporating the cadastral graphic representation or an alternative georeferenced representation — or the boundary-fixing procedure of article 200. If a neighbour objects, the matter can end up in court. A boundary discrepancy with foreseeable objection is reason enough not to sign yet.
13. A different number of floors
An added floor is always major works and often affects height and buildability parameters. It is among the cases where subsequent legalisation is least likely.
14. A registered building that may still have planning problems
This bears repeating because it is counter-intuitive: the fact that a building is registered does not guarantee that it complies with the plan. It may have been registered by the antiquity route, or registered correctly and later left outside planning by a change of plan. Registration evidences registry publicity, not planning compliance.
Three statements we hear every week — and that are wrong
“It’s not in the Registry, so it’s illegal.” Wrong. The absence merely means nobody declared the works. They may have an impeccable municipal licence and simply never have been registered, which is entirely possible because a declaration of new construction has not always been required in practice.
“It’s in the Cadastre, so it’s legal.” Wrong, and probably the most expensive of the three mistakes. The Cadastre records the constructions it detects in order to tax them. An unlicensed pool pays IBI exactly like a licensed one. Cadastral presence is not a planning consent.
“We did a declaration by antiquity, so it’s legalised now.” Wrong. Article 28.4 of Royal Legislative Decree 7/2015 allows a building against which legality can no longer be restored to reach the Registry, but it does not make what was built compliant with the plan. The provision itself requires the registrar to notify the town hall and, where applicable, to record the outside-planning situation. It is a registry solution, not a planning one. We set out the full regime in building or renovating without a licence in Spain.
What documents must be requested
- Up-to-date registry extract (nota simple): ownership, charges and the current registered description. We explain how to request and read it step by step.
- Registry certificate (certificación registral) where greater historical detail or stronger evidential value is needed, for example to reconstruct the property’s history.
- Descriptive and graphic cadastral certificate: surface areas, year of construction by element and graphic delimitation of the plot. It is the document that makes comparison with the registry extract possible.
- Plans: project drawings if they exist, otherwise a current survey by a technician.
- Building licence and, where applicable, first or second occupancy licence.
- Technical certificate of surface areas and the condition of the building, issued by an architect or technical architect.
- Certificate of antiquity where the article 28.4 route is to be used, normally supported by historical aerial photography.
- Municipal planning information: planning certificate stating classification, designated use and applicable parameters.
- Certificate of absence of planning enforcement proceedings, where the case warrants it. We explain its use in the urban planning compliance certificate.
- Further documents depending on the case: owners’ community resolutions where the works affect common elements, sectoral authorisations (roads, coast, watercourses) and, on rustic land, a declaration of community interest where required.
Who should resolve the discrepancy: buyer or seller?
Legally, the seller is obliged to deliver the property in the agreed condition. But that resolves nothing on its own, because a standard arras contract rarely stipulates the property’s descriptive status expressly.
In practical terms, it is the buyer who has an interest in the problem being resolved before the deed, for three concrete reasons. The first is that the negotiating position reverses completely on signature: before the deed the seller needs to close the sale; afterwards, the seller needs nothing. The second is that financing depends on it: Spanish banks rarely grant a mortgage where the registered description does not match what has been valued. The third is that the consequences of unlicensed works fall on whoever owns the property at the time, not on whoever built them.
The rule we apply in the office is straightforward: anything affecting planning legality or financing must be resolved before the deed; anything purely documentary can be resolved afterwards, provided it is contractually covered — with a firm deadline, an identified responsible party, an allocated cost and, where the amount justifies it, retention of part of the price. A verbal undertaking that “the seller will sort it out” is not cover. How this is drafted into the contract is explained in the arras contract: 15 clauses to check before you sign.
Decision tree
Registry = Cadastre = physical reality
→ Continue with the rest of the ordinary legal review.
They do not match
→ 1. Identify the discrepancy precisely: does it concern the plot or the building? the area, the boundaries or existence itself?
→ 2. Analyse the planning position: was there a licence? when were the works carried out? has the restoration period expired? are proceedings pending?
→ 3. Determine whether the discrepancy can and should be corrected, and by which route: cadastral declaration, article 199, article 201, article 202, declaration by antiquity, or municipal legalisation.
→ 4. Calculate the real costs: technical fees, notary, registry and AJD, which in the Valencian Community is 1.40% since 1 June 2026.
→ 5. Establish who bears them and within what deadline.
→ 6. Adapt the arras contract accordingly.
→ 7. Verify actual compliance before executing the deed — do not rely on the promise.
Where step 2 reveals that the works cannot be legalised and the restoration period has not expired — the typical case of a recent building on non-developable land — the tree ends there. That is not a problem solved by retaining part of the price.
Frequently asked questions
What is the difference between the Land Registry and the Cadastre?
The Registry publishes rights: who owns the property and what charges affect it. The Cadastre describes the property primarily for tax purposes: surface areas, use, age and cadastral value. They are independent, administered by different authorities, and may not match. Since Law 13/2015 a coordination procedure exists, but many older properties remain uncoordinated.
What happens if the pool does not appear in the Land Registry?
On its own, nothing conclusive. It means nobody has registered the works. What matters is whether the pool had a municipal licence and, failing that, whether the period for the town hall to require restoration of planning legality has expired. In the Valencian Community that period is, as a general rule, fifteen years from full completion, with significant exceptions where no period applies at all, among them non-developable land.
Is a construction illegal if it does not appear in the Registry?
Not necessarily. The Registry reflects only what someone has applied to register. A construction with a perfectly valid licence may never have been registered. Planning legality is evidenced at the town hall, not at the Registry.
Is a construction legal if it appears in the Cadastre?
Not necessarily. The Cadastre records what exists so it can be taxed, regardless of whether it has a licence. Its description has tax effects, not authorising effects.
Can I correct the surface area in the Cadastre myself?
The owner can and must declare alterations affecting the property, using the corresponding cadastral declaration form. Article 18 of the consolidated Cadastral Law also governs the discrepancy-correction procedure, which is initiated by the authority but can be prompted by bringing the matter to its attention. Weigh the effect first: a larger surface area means a higher cadastral value and therefore more IBI, and may trigger review of earlier years.
How much does it cost to correct a discrepancy?
Entirely dependent on the case. A simple cadastral update may be free apart from technical fees. A declaration of new construction by antiquity usually falls between €1,500 and €3,500, including technical certificate, notary, registry and AJD. An article 201 procedure involving neighbouring owners, or a boundary-fixing procedure, is considerably more expensive and slower. A planning legalisation may require a full project.
How long does it take?
A simple cadastral update, weeks. A declaration by antiquity, one to three months in normal conditions, including obtaining the technical certificate. A notarial procedure under article 201, several months. One more reason not to set a thirty-day deadline to the deed in the arras contract while a discrepancy remains unresolved.
Can the bank refuse my mortgage because of a discrepancy?
Yes, and it happens frequently. The valuer measures what exists and the lender compares it with the registered description. If the valued property is 214 m² and the registered property is 180 m², the lender may require the difference to be registered first. It is one of the reasons to have the question resolved before committing contractually.
Legal sources
- Decree of 8 February 1946, Spanish Mortgage Law (Ley Hipotecaria): articles 9.b), 10, 199, 200, 201, 202 and 203 (BOE).
- Royal Legislative Decree 1/2004, consolidated Cadastral Law: articles 3, 11, 13, 14 and 18 (BOE).
- Law 13/2015 of 24 June, reforming the Mortgage Law and the consolidated Cadastral Law (BOE).
- Joint Resolution of the Directorate General of Registries and Notaries and the Directorate General of the Cadastre of 29 October 2015, on information exchange and graphic coordination (BOE).
- Royal Legislative Decree 7/2015, consolidated Land and Urban Rehabilitation Act: article 28(1) and 28(4) (BOE).
- Legislative Decree 1/2021, consolidated Valencian Land Use, Planning and Landscape Act (TRLOTUP): restoration of planning legality and the outside-planning situation (DOGV).
- Law 5/2025 of 30 May of the Generalitat: AJD rate of 1.40% since 1 June 2026 (DOGV).
- Cadastre Electronic Office and the Association of Registrars, for cadastral certificates and registry extracts.
Verification before purchase
We systematically cross-check the registry extract, the cadastral certificate and municipal planning information before our clients sign anything, and adapt the contract when a discrepancy appears. We work in English, Swedish, Norwegian, Danish and Spanish.
Read more about our property purchase service or run your figures with our free tools: buying costs and plusvalía municipal.
Colás Abogados / Advokater — Hugo Gutiérrez Colás, Lawyer no. 6.539 ICALI
Calle Mozart 9, 03581 Alfaz del Pi (Alicante)
Email: [email protected]
Telephone: +34 629 549 430
Web: www.colas-abogados.com
Author: Hugo Gutiérrez Colás, Lawyer no. 6.539 of the Alicante Bar Association. Published 20 August 2026. Last legal review: 20 August 2026.
This article is informative in nature and does not constitute legal advice on a specific case. The classification of a discrepancy and the appropriate route to correct it depend on the documentary and planning analysis of each property.