You see a flat listed at 100 m². You order the nota simple and the Land Registry says 85. The first reaction is usually that someone has inflated the figure. Sometimes there is something to clear up, but often there isn’t: each document measures something different, by its own rules.
In Spain, the same flat can carry at least three figures: the built area recorded in the Catastro, the area stated in the Land Registry (Registro de la Propiedad) and the usable area, which is the floor you actually walk on. Knowing how to read them saves you a surprise after you have paid the reservation deposit.
Built area in the Catastro
The Catastro is an administrative register run by the Spanish tax authorities. Its job is to describe properties for tax purposes, mainly to set the cadastral value and, from it, the IBI property tax.
The rule is set out in Royal Decree 1020/1993 (rule 11.3). Built area is everything inside the outer line of the perimeter walls and, where a wall is shared with the neighbour, up to the centre line of that party wall. Light wells are deducted. In other words, it includes the thickness of the outside walls and of every internal partition.
Three details explain many of the differences:
- Terraces and balconies. Covered ones count at 50% of their area, and at 100% if they are closed on three of their four sides. The rule only mentions covered elements: an open-air terrace is not part of that count.
- Ceiling height. In homes, spaces lower than 1.50 m are not counted, which is common in attics and under sloping roofs.
- Common areas. The figure on the cadastral record is usually the private area plus a share of the building’s common areas (entrance hall, stairs, landings). The Catastro itself states that this share is approximate and only used for cadastral valuation.
That last point causes the most confusion. On the Catastro’s official website you can see the breakdown: how many square metres belong to the flat and how many are a share of common areas. It is worth checking before you compare it with any other figure.
The figure in the listing
On property portals, the square metres are entered by whoever places the ad. Very often it is the Catastro’s built area, because it takes a minute to look up. But it can also be the seller’s own measurement, a figure that includes the whole terrace, or one that adds the common areas. The listing rarely says which one it is.
When the seller is a professional, Royal Decree 515/1989 requires them to make available to the buyer a description of the home that states its usable area. You are entitled to ask for it.
Area in the Land Registry
The Land Registry is a separate institution, independent from the Catastro. Its role is legal: it records who owns the property, what charges it carries (a mortgage, an attachment) and how it is described.
The area shown in the nota simple comes from the deeds recorded over the years, usually the deed that declared the building and divided it into flats, and the later sales. In a building from the 1960s, that description may be more than fifty years old.
Read the wording carefully, because the nota simple may give usable area, built area or both. Coming from the Registry does not make it the usable area.
There is another little-known point. Spain’s Supreme Court has repeatedly held that the Registry’s legal guarantee does not extend to physical facts such as floor area. The Registry protects ownership; it does not guarantee the square metres. Those figures rest on what the parties declared when the deed was signed.
Since 2015 there has been a system to coordinate the Catastro and the Land Registry, but many properties are still not coordinated, so the two descriptions can drift apart for years.
Usable area
Usable area (superficie útil) is the closest thing to what most people picture when they read “square metres”: the floor space you can actually use inside the home.
There is no single definition for every purpose. One of the most widely used is in Order ECO/805/2003, which valuation companies follow. Under it, usable area is the floor enclosed by the inner face of the outside walls, excluding:
- fixed internal partitions,
- columns and other structural elements,
- ducts with a cross-section above 100 cm²,
- areas with less than 1.50 m of headroom.
The same order adds half of any covered private outdoor space (terraces, balconies, utility balconies) and leaves out uncovered ones. Other rules, such as those for subsidised housing or local planning bylaws, have their own methods and sometimes cap how much terrace can be counted.
So you cannot assume the usable area always sits between the Catastro figure and the Registry figure. It depends on the flat and on how each one was measured. If you need to know the real space, the only reliable answer is to measure it: on site, or with a survey by an architect or building surveyor.
An example: 100 m² in the Catastro, 85 m² in the Land Registry
Picture a flat in a 1965 building in Valencia. The listing says 100 m², which is the Catastro’s built area. The nota simple says 85 m². That is a 15 m² gap, 15% of the advertised figure.
There can be several explanations, and they are not mutually exclusive:
- Common areas. If the Catastro breakdown attributes 12 m² to common areas, the flat itself has 88 m² of built area. The gap with the Registry shrinks to 3 m².
- Type of area. The 1965 deed may have described the flat by its usable area, while the Catastro uses built area.
- Age of the documents. The Registry description was written decades ago and never updated. The Catastro, on the other hand, may have been revised.
- Building work. An enclosed gallery or a merged side room may appear in one document and not in the other.
A gap like this is not, on its own, an irregularity. But you should not accept it as normal without understanding it either. It can also hide an extension built without a permit, a terrace enclosed without authorisation or a plain mistake. And check that both figures describe the same space: sometimes one includes a storage room or an attached parking space and the other does not.
The effect on price shows up quickly. If the flat costs €300,000, that is €3,000/m² over 100 m², about €3,530/m² over 85 m² and €4,000/m² if the usable area were 75 m². The flat is the same; only the figure you compare against changes.
Older buildings, new builds and penthouses
Older buildings. This is where gaps are most common, because the documents were drawn up at different times and by different methods. In Valencia it happens often in buildings in the Ensanche, Ruzafa, Ciutat Vella or the Cabanyal that have been renovated several times over the years.
New builds. The newer the building, the closer the figures tend to be. The documents are recent, they come from the same project plans and the measurements were taken with current methods. Even so, there is no guarantee that the Catastro and the Registry will match to the square metre.
Penthouses and terraces. Look more carefully here. In the Catastro, a covered terrace counts at 50% and an uncovered one is not part of the built area under rule 11.3. In a valuation, usable area adds half of the covered terrace and nothing for the uncovered part. In a listing, however, the whole terrace may be added to the interior. A “120 m²” penthouse can be a 75 m² flat with a 45 m² terrace. And if the terrace has been enclosed, find out whether that work had a permit.
Before you reserve: what to check
- Ask for the cadastral reference. With it, or with the address, you can look up the property’s non-protected data for free on the Catastro’s official website: area, use and year of construction. Look at the split between private area and common areas.
- Ask for a recent nota simple. It is requested from the Land Registry, in person or online through the Registradores website, identifying the property by its address, its registry details or its IDUFIR code. It costs very little. Read the description and note which area it gives.
- Compare like with like. Built area with common areas, built area without them, or usable area. Check whether any figure includes a storage room, parking space or terrace.
- If the gap is large, ask before you commit. Seeing that the numbers don’t match is not enough: you need to know why. The seller or the agency should be able to explain it before you sign the reservation or the arras contract.
- If the paperwork doesn’t settle it, measure. An on-site measurement or an architect’s survey answers the question. If you are taking a mortgage, the valuer will measure too, although that usually happens after the reservation.
None of these figures, on its own, guarantees the interior space you will get.
Frequently asked questions
What is the difference between usable and built area in Spain?
Built area includes the thickness of the outside walls and partitions, and in the Catastro it usually adds a share of the common areas. Usable area is the floor space you can use inside the home, without walls, partitions or columns.
Which area prevails, the Catastro’s or the Land Registry’s?
They are registers with different roles. The Catastro describes the property for tax purposes; the Land Registry gives legal certainty about ownership and charges. Under Supreme Court case law, the Registry’s legal guarantee does not cover physical data such as floor area. If there is a significant gap, the sensible step is to measure.
Is it normal for the figures not to match?
It is common, especially in older buildings, and it does not always point to a problem. But there is no “normal” percentage that applies to every flat. Every gap should have an explanation.
Conclusion
In property, the number of square metres is not enough. You need to know what it refers to.
A flat listed at 100 m² can have noticeably less usable area without that meaning anything is wrong. What matters is that buyers know what they are buying and check it before they pay the deposit, not after.