Declare an additional dwelling in Catastro (division, extension or change of use)

What you need to have ready

• Cl@ve (PIN o Permanente), certificado digital o DNIe that works.
• Referencia catastral of the property (from the IBI or get it on sedecatastro.gob.es).
• Actual completion date of the works or the change of use.
• Plans with surfaces for each dwelling and for the whole property.

Documentation

1. Identity: DNI/NIE of the declarant (and signed authorisation if a representative files it).
2. Title: escritura de propiedad; if it exists, división horizontal inscrita.
3. Works/use: licencia urbanística or declaración responsable and certificado final de obra.
4. Plans: layout and surfaces (útil/construida) signed by a technician if you can.
5. Habitability: cédula or equivalent document (if your CCAA requires it).
6. IBI/Reference: latest recibo to cross-check data.

Step by step

1. Go to https://www.sedecatastro.gob.es > Trámites > Declaraciones. Identify yourself with Cl@ve or certificado.
2. Choose the Declaración de alteración catastral (bien urbano). Enter your details and the referencia catastral.
3. Mark the alteration: creación de vivienda adicional by division/extension/change of use. Enter the fecha de fin de obra.
4. Fill in surfaces: total property and each resulting dwelling; add annexes (trastero/garaje) if relevant.
5. Attach PDFs: licencia/DR, plans, certificado final de obra, escritura (and división horizontal if there is one) and, if applicable, cédula.
6. Sign and register. Save the justificante con CSV. Watch the DEHú (https://dehu.redsara.es) for any requerimientos and, if needed, use "Aportar documentación a un expediente" on the Sede.

Time-saving tips

• Upload clear, lightweight PDF (preferably <10 MB); compress before uploading if needed. Avoid blurry photos.
• If you have plans signed by a técnico, you'll avoid back-and-forth over surface doubts.
• Use the same date across all documents (fin de obra/licencia) to reduce chances of requerimientos.
• Check the domicilio de notificaciones is correct; communications will go via DEHú.

Common mistakes that will mess up the process

• Declaring without licencia or DR when the work required it: you'll get a requerimiento for sure.
• Not detailing surfaces per unit (only listing the total): they'll stop the file for lack of breakdown.
• Incoherent dates (works finished before the licence): smells bad and ends in subsanación.
• Forgetting the cédula de habitabilidad where it's mandatory: another requerimiento.
• Missing the plazo de 2 meses thinking nothing will happen: later you get fines and IBI complementarias.