Spain Cadastre 2026: Who Must Refile, and Who Pays If Nobody Did

No cadastral rule changed for 2026. What changed is how easily the Catastro spots work that nobody declared. The obligation sits in the Texto Refundido de la Ley del Catastro Inmobiliario and falls on the owner, whether or not the ayuntamiento issued a licence and whether or not a notary was involved. Planning permission and the cadastral record are separate systems, and they do not reconcile themselves.

Alteration	Two-month clock starts the day after	Effect on valor catastral
New build, extension, reform, rehabilitation	The works are certified complete (final de obra)	Up
Pool, garage, porch, glazed terrace	The works finish	Up
Demolition or partial teardown	The works finish	Down
Change of use	The change-of-use authorisation is granted	Usually up
Segregation, division, joining of plots	The deed is signed	New records created

Since Orden HAC/1293/2018 there is one form for all of it. The old 901N, 902N, 903N and 904N models were folded into a single modelo 900D, filed through the Sede Electronica del Catastro with a digital certificate or Cl@ve. A lawyer or gestor can file for you on a signed authorisation. Filing on time costs nothing, and the Catastro has six months to resolve.

One exception: where a notary transmits a straightforward sale electronically, the ownership record updates by itself. Physical changes to the building never do. For the difference between the Catastro and the Registro de la Propiedad, see our explainer on the referencia catastral.

Two months, then a penalty

New builds catch people out most often. The clock starts the day after the works are certified complete, not the day you move in.

Missing the deadline is a tax infringement under articles 70 and 71 of the same law. The penalty is a fixed euro band written into the statute rather than a percentage of the work, with a separate per-item scale where a declaration goes in incomplete or inaccurate. Current amounts are in the consolidated text on the BOE. In practice the fine is rarely the expensive part.

Regularisation, and why the bill lands on the new owner

The Catastro has run a regularisation procedure since 2013 across the whole country, the Basque Country and Navarre excepted, since both keep their own cadastres. It sets aerial imagery, municipal records and supply-company data against the cadastral file, opens a case on any discrepancy and corrects the record without waiting for the owner. Pools, porches, closed-in terraces and converted garages all read clearly from an orthophoto.

The fee is EUR 60 per property regularised, charged to whoever holds the status of IBI taxpayer in the year the file opens. It replaces the sanction rather than stacking on top of it, which is the one piece of good news here. Where the Catastro acts through an ordinary inspection instead, the articles 70 and 71 regime applies as normal.

The effective date is the problem. The corrected description applies from the day after the work was actually done, not from the day it was found, so the ayuntamiento re-bills IBI for every year still open. That is four years in practice, with late-payment interest on each of them.

This is what catches foreign owners. A pool dug in 2011 by a Spanish seller who never declared it, a sale in 2023, a letter in 2026 with your name on it. The person who did the work is not the person who pays.

Valor catastral is never one bill. It feeds:

• IBI, charged annually as a municipal percentage of it. See how IBI is calculated.
• Plusvalia municipal on sale, which uses the land element of the value.
• The imputed income base for non-residents, 1.1% or 2% of valor catastral. That return goes in once a year, not quarterly. See our Modelo 210 guide and annual property taxes.
• Valor de referencia, the ITP floor since 2022. A different number, but the Catastro builds it from your property's recorded characteristics, so a surface correction feeds into it.

Our property tax calculator gives you the annual shape. Arrears go on top.

Check the surface before you sign

Pull the cadastral record for the reference on the nota simple and compare three things: the built surface at the Catastro, the built surface at the Registro, and the house standing in front of you. Small differences between the two registers are common and usually harmless. A terrace that has become a bedroom, or 40 m2 you cannot account for, is not.

Ask the seller for the works licence and the certificate of completion. If neither exists, a cadastral declaration will record and value the extension without legalising it, and the ayuntamiento can still act. Older work can sometimes be settled through a declaracion de obra nueva antigua, though that route narrows sharply on protected rustic land and inside the coastal easement, where the power to order demolition does not always expire.

Our guides to reading a nota simple and the 12-step non-resident checklist place this check in the timeline. If you are the one extending, price the work with renovation costs per m2 and budget the declaration alongside the builder.

Common questions

Who files the declaration, the buyer or the seller?

The owner at the time of the alteration is legally responsible. In practice the Catastro charges the fee, and the ayuntamiento the arrears, to whoever owns the property when the file opens. There is no realistic route back to a seller who left three years ago.

Does the work need a building licence before I can declare it?

No, and that surprises people. The two systems are separate. The Catastro will record and value an unlicensed extension without complaint. That does not legalise anything, and the planning breach stays live at the ayuntamiento.

Next steps

Before your next offer, pull the cadastral record for the reference on the nota simple and compare the built surface with the floor plan. If the numbers differ, send us the address and we will check it before you sign.