Censo de entidades: alta y cambios en AEAT (con NIF provisional/definitivo tras Registro Mercantil)

What you need to have to hand

1. Escritura de constitución y estatutos en PDF (better the notarial electronic copy).
2. Certificación negativa de denominación (if you still need the NIF provisional).
3. Asiento de presentación o inscripción del Registro Mercantil (for the definitive NIF).
4. DNI/NIE del representante y certificado digital de representante (or electronic apoderamiento in AEAT).
5. Justificante del Modelo 600 (ITPAJD constitución: exempt, but you file it).
6. Documento del domicilio fiscal (contract, deed or a recent bill).

Documentation

• Modelo 036 online for: solicitud de NIF provisional, comunicación de NIF definitivo and alta en el censo (IVA, retenciones, IAE, domicilio, administradores y socios significativos).
• Registro Mercantil: escritura, liquidación del ITPAJD and payment of aranceles registrales.
• If you’re not exempt from IAE: Modelo 840/848 (alta and communication of turnover).

Step by step

1. Request NIF provisional at AEAT: go to the Sede de la AEAT and submit Modelo 036 (trámite de solicitud de NIF para personas jurídicas). Attach the escritura and the certificación de denominación. They usually give a tarjeta NIF provisional almost immediately if everything is OK.
2. Register at Registro Mercantil: file the escritura at your provincial Registro Mercantil. They give you an asiento de presentación and, in a few days, the inscripción. Watch out for fees and for requests to fix statutes.
3. Switch to definitive NIF and census registration: go back to Modelo 036, file a variation to communicate NIF definitivo, set domicilio fiscal, epígrafe IAE, IVA (régimen general/simplificado/exento) and retenciones (if you will have employees or professionals). Attach the certificación de inscripción.
4. IAE if needed: if you’re not exempt, file modelo 840/848 before starting activity. If you are exempt (usual at the start), don’t file it, but mark the exemption clearly on the 036.
5. Keep everything: receipts for the 036, tarjeta NIF definitiva and, if applicable, 840/848. Tell the bank, suppliers and put the definitive NIF on invoices.

Time-saving tricks

• Have the certificado de representante ready. For companies, the Cl@ve of an administrator usually won’t do unless they’re empowered. Without it you’ll need a face-to-face appointment.
• Light attachments: upload PDFs under the Sede size limits; if a file is heavy, use PDF/A or compress it.
• Set IVA correctly: if you don’t owe recargo de equivalencia, don’t tick it “just in case”. Changing it later is another 036 and can cause headaches on periodic returns.
• Epígrafe IAE: pick the one for your main activity. If you add business lines, file a variación censal before invoicing.
• Clear fiscal address: if you work from home, consider a domiciliation in a coworking for notifications; changing address later means another 036 and possible missed letters.

Typical mistakes that will mess up the process

1. Not switching to definitive NIF after registering: AEAT leaves you in limbo and can fine you (from 200€).
2. Not reporting directors/shareholders on the 036: if they’re missing they’ll ask you to correct and some tax registrations will be blocked.
3. Choosing the wrong VAT scheme: marking exemption without legal basis or not marking withholdings when you’ll have employees. Then come the requerimientos.
4. Filing late: the census registration must be before starting activity. If you invoice without registration, fine and trouble.
5. Trying to sign with an invalid Cl@ve: if the entity lacks a certificado de representante or apoderamiento, the Sede will reject the final step. Better sort this first.