Register an additional dwelling in Catastro (Gestión 12)

What you need to have to hand

1. Cl@ve, certificado digital or DNIe that works. Without one, you need a presencial cita.
2. Referencia catastral of the parent property (14 characters, it’s on your IBI or on the Sede del Catastro).
3. Actual date of completion of works or date of the escritura. They will ask for it.
4. Areas of the new dwelling by floor (m2 built and useful if you have them).

Documentation

• DNI/NIE of the owner. If you act for someone else, autorización de representación and their DNI.
• Escritura de obra nueva and/or división horizontal (or proof of filing at the Registro).
• Licencia de obras or declaración responsable and, if available, licencia de primera ocupación.
• Certificado final de obra signed by the technician (when it applies).
• Planos acotados with areas and layout (legible PDF).
• Photos of the additional dwelling and accesses.
• Recibo del IBI of the parent property (to cross-check data).

Step by step

1. Go to https://www.sedecatastro.gob.es/ > Trámites > Declaraciones. Identify with Cl@ve or certificado.
2. Choose Alteración de bienes inmuebles urbanos and the option Alta/modificación de construcción. Enter the referencia catastral of the parent property.
3. Complete the new dwelling data: use = Residencial, areas per floor, number of entities created, date of end of works/escritura and a short description.
4. Attach PDFs: escritura/licencia, certificado final de obra (if any), planos and photos. Better to upload clear documents and split files to avoid size limits.
5. Review and sign. Download the justificante and save the nº de expediente. Track it in Mis expedientes.
6. If you go in person, book a cita at the Gerencia del Catastro from the sede and bring the printed form and copies. They will stamp it at registro and give you an entrada number.
7. If you get a requerimiento, reply within the deadline (normally 10 días hábiles) uploading what they ask. Once resolved, download the certificación descriptiva y gráfica and check your IBI for the next ejercicio.

Tricks that save you time

• If there’s a división horizontal, at least present the asiento registral (proof of filing at the Registro). Avoid silly requests.
• Provide a simple plano with clear areas per floor. If the technician gives it, even better.
• Use Chrome/Edge; the Sede sometimes chokes on other browsers and heavy files.
• If the Ayuntamiento is colaborador with Catastro, ask if they already sent the info. If not, declare yourself and attach their licencia.

Common mistakes that can mess your case

• Presenting late (more than 2 meses): risk of fine and IBI complementaria.
• Uploading illegible PDFs or a single 50 MB file: the sede fails and you waste time.
• Not proving the legal configuration (no escritura for a división horizontal when needed): expediente stuck.
• Forgetting the correct referencia catastral: you declare the wrong property and must correct it.
• Not checking the notificaciones inbox: they request info, you don’t reply, and they archive the expediente.