Social Security contribution bases report (Seguridad Social)

What you need to have handy

1. DNI or NIE (the same one the Seguridad Social has).
2. Cl@ve, Certificado digital or DNIe if you want to do it on the spot.
3. Mobile number registered with TGSS if you're going in via SMS.
4. Número de la Seguridad Social (NAF) so you can check you're looking at your record.
5. Email if you want the PDF sent to you.

Documentation

• Electronic ID: Cl@ve PIN/Permanente, Certificado digital or DNIe (with PIN and reader).
• Mobile phone registered with TGSS (only if you use SMS).
• NIE/DNI and date of birth (they ask for these for the SMS).
• Payslips or quota receipts (you don't submit them, but they help you check if something looks wrong).

Step by step

1. Go to Import@ss: https://importass.seg-social.es/tramites/informe-de-bases-de-cotizacion and click Iniciar.
2. Choose how to ID: Cl@ve, Certificado or DNIe. If you choose via SMS, enter DNI/NIE, date of birth and your registered mobile to get the code.
3. Select period (dates or years) and régimen (General, Autónomos/RETA, etc.). If you've worked several jobs in the same month, check they all show up.
4. Click Generar and download the PDF with CSV. You can also email it to yourself from that screen.
5. No electronic ID? Go to the Sede: https://sede.seg-social.gob.es/wps/portal/sede/sede/Ciudadanos/Informes+y+certificados, enter Informe de bases de cotización and use Sin certificado to request postal delivery to the address TGSS has for you.

Time-savers (tricks)

• Always download with the CSV: that avoids disputes about authenticity. The CSV validates on the Sede.
• If the SMS doesn't arrive, check and update your contact details in Import@ss (phone and email). With Cl@ve/certificado you can change them in two minutes.
• If it's for a bank, request the full calendar year or the exact range they ask for and avoid doing it twice.
• Try another browser if signing or download fails. Chrome/Edge usually behave better than Safari.
• If the last month doesn't appear, wait until mid next month: many companies close cotisations late and TGSS won't reflect them immediately.

Common mistakes that ruin the process

• Trying SMS when your mobile isn't registered with TGSS: the code never arrives and you waste time.
• Handing in a PDF without the CSV: banks and authorities can reject it.
• Assuming a missing cotisation is fraud when the month is simply not closed yet: it's a timing issue.
• Requesting a single month when they asked for several years: you'll have to run it again.
• Not checking the régimen: if you're both autónomo and employee, get both or you'll miss data.