Before selling in Spain: why your property must match the Catastro, the Registro and reality

I see this scene almost every week in my office. Someone wants to sell their home on the Costa Blanca, a buyer comes along, everything is going well… and suddenly the deal stalls because the property «on paper» is not the same as the property in reality. There is a pool that does not appear anywhere, a covered porch that was turned into a bedroom, a few extra square metres. And that, which seems like a minor detail, can bring an entire sale crashing down.

The good news is that there is a solution, and it can almost always be sorted out before the property goes on the market. I will explain it step by step, without technical jargon.

What does «declaring a new build» mean?

Declaring a new build simply means formally recording that a construction exists on a plot of land. When the land was purchased or inherited, the paperwork may have shown only bare land, or a smaller house. If something was then built or extended, that change needs to be reflected. Until it is, the real property and the registered property do not match.

Think of your property as having three «photographs» that should all be identical: physical reality (what is actually built), the Registro de la Propiedad (what is officially yours and free of encumbrances) and the Catastro (what the tax authority has on record for charging property tax). When all three photographs align, selling is straightforward. When they do not, the problems begin.

The Catastro and the Registro are not the same thing (and they sometimes barely talk to each other)

Many people confuse them, so let us separate them clearly. The Catastro falls under the Tax Agency and describes the property physically: floor area, use, location. It is what determines, for example, your IBI (annual property tax) bill. The Registro de la Propiedad, by contrast, records who the owner is and what encumbrances exist on the property (mortgages, charges, easements).

For years they operated independently and it was normal for them to diverge. Since Ley 13/2015 both are required to coordinate: when the graphic description of a property is registered, the Registro and the Catastro agree on its boundaries and floor area. That is why today, before selling, it is worth checking that both photographs say the same thing as reality.

Two routes: completed build and build «by prescription»

Not all builds are declared in the same way. The law (the Consolidated Land Act, known as TRLS, in its article 28) provides for two routes, and knowing which one applies to you makes a significant difference to the process.

1. Completed new build (with a licence)

This is the standard route when the construction was carried out with a municipal building licence and a final completion certificate. It is declared before a notary by submitting that technical documentation and is then registered at the Registro. This is the clean path: there are documents proving that everything was done by the book.

2. New build by prescription (art. 28.4 TRLS)

This is the most common situation with older coastal properties. Here the construction or extension has no licence, but so much time has passed that the authorities can no longer require it to be demolished. When this occurs, the law allows registration by submitting a technical certificate (from an architect or quantity surveyor), a catastral certification or a notarial deed proving that the build was completed by a specific date.

A crucial distinction: registering a build by prescription is NOT the same as «legalising» it for planning purposes. These are different things. Registration allows you to sell, mortgage or inherit the property normally; the planning status of the construction remains as it is. That is why it is important to have your specific case reviewed before assuming anything.

Why this can block a sale (or an inheritance)

When the square metres do not add up, the problems appear at the worst possible moment: with the buyer already in front of you. Here is what typically happens:

• The buyer's bank values the property and finds that the actual floor area does not match the Registro: it either reduces the mortgage or refuses to grant it.
• The buyer, quite reasonably, loses confidence and walks away, or demands a price reduction.
• The home insurance policy may not cover the part of the property that is not declared.
• In an inheritance, the property cannot be registered in the heir's name until the description is correct.

All of this can be avoided by doing your homework in advance. A sale that falls through for a registration issue costs far more — in money and in stress — than regularising in good time.

How much does it cost and how long does it take (honestly)

Let me give you an honest guide, because every case is different. Several professionals and bodies are involved in regularisation, each with their own costs: the technical expert who signs the certificate (architect or quantity surveyor), the notary, the Registro de la Propiedad, the tax on the deed (Actos Jurídicos Documentados, a form of stamp duty) and the update at the Catastro.

In terms of time, once the technical documentation is ready, the process generally moves within a range of a few weeks to a couple of months, depending on the workload at the Registro and the Catastro. What takes longest, almost always, is getting the technical side properly prepared. That is why I insist: starting early is the best investment.

How to regularise the Catastro–Registro–reality chain

This is the logical order I follow when I handle a case like this:

1. Identify the discrepancy: I request an up-to-date nota simple (property extract) from the Registro and compare it with the catastral reference and the actual property.
2. Commission the technical certificate: an architect or quantity surveyor certifies the description of the build and, if the prescription route applies, its completion date.
3. Choose the correct registration route: for small discrepancies, registering the graphic representation (art. 199 of the Ley Hipotecaria) is usually sufficient; for large discrepancies, a specific notarial procedure may be required (art. 201). This is where sound judgement saves rejected applications at the registry.
4. Execute the new-build declaration deed (completed or by prescription) before a notary, with the technical documentation.
5. Register at the Registro de la Propiedad and confirm that the registered description now matches reality.
6. Update the Catastro so that the floor area and use are aligned, ensuring the problem does not resurface in the next transaction.

Checklist before putting up the for-sale sign

If you are thinking of selling — or inheriting — a property in Spain and are not sure whether your paperwork is in order, get in touch and we will go through it together. I would rather help you get ahead of the problem than put out a fire afterwards. That is how I work: first understand your case, then prevent, and only then act.