Telematic legalisation of books at the Registro Mercantil

What you need to have to hand

1. Certificado digital de representante (FNMT or DNIe) or Cl@ve Firma that works.
2. Books in PDF/A for the financial year: Diario, Inventarios y Cuentas Anuales, Actas and, if applicable, Socios/Acciones.
3. Financial year data: closing date and the provincial Registro Mercantil competent (registered office).
4. Card to pay the Registro arancel.

Documentation

• Libro Diario for the full financial year in PDF/A.
• Libro de Inventarios y Cuentas Anuales (opening balance, trial balances, annual accounts).
• Libro de Actas (if there are meetings/administrative bodies; one per year).
• Libro Registro de Socios/Acciones Nominativas (SL/SA with nominative shares).
• NIF and company name exactly as registered.
• Email address for notices and downloads.

Step by step

1. Close the accounts for the financial year. Check there are no pending entries.
2. Generate the PDF/A files for each book. No passwords or weird embedded signatures that block them.
3. Create the telematic expediente with the Colegio de Registradores tool (Legalia): select the year, add books, and generate the zip with the fingerprint.
4. Go to https://sede.registradores.org > Registro Mercantil > Legalización de libros and identify yourself with certificado or Cl@ve Firma.
5. Choose the Registro Mercantil (province of the registered office), enter the closing date and upload the zip of the expediente.
6. Confirm and pay the arancel by TPV (or generate carta de pago if your RM allows). Download the receipt with CSV and entry number.
7. Wait for the qualification (usually a few days). When it's ready, access your expediente and download the diligencias de legalización (signed PDFs). File them with the books.

Time-saving tricks

• Do it as soon as you close: don't wait until April. There are peaks and the sede can slow down.
• One book per year and neatly ordered. If you mix years or insert blank pages to "fill", they'll reject it.
• File size: if the PDF is huge, compress it without losing legibility. The system has limits.
• Check the certificate: make sure it's not expired or revoked. Half of rejections are due to invalid signatures.
• Don't confuse: legalising books is not the same as depositing accounts. Different procedures and menus.

Typical mistakes that will mess up the procedure

1. Missing the 4-month deadline: you can submit late but it will be recorded. No automatic fine usually, but it looks bad to third parties.
2. Uploading password-protected PDFs or not in PDF/A: automatic rejection. Regenerate the files.
3. Selecting the wrong Registro Mercantil: if it's not the one for your registered office, they'll toss it.
4. Mixing entries from several years: formal defect. Each year needs its own book.
5. Assuming SII covers this: wrong. SII is AEAT; this is Registro Mercantil.
6. Not saving the receipt and diligencias: you'll be asked for them later in audits or by third parties. Keep everything with its CSV.