What is SII?

What it is and its legal basis

Since 1 July 2017, certain Spanish companies no longer keep their VAT record books themselves: they keep them within the Spanish Tax Agency's e-office, sending the details of each invoice almost in real time. That system is the SII.

It was introduced by Royal Decree 596/2016 of 2 December (BOE-A-2016-11575), which amended the Spanish VAT Regulation, and its technical specifications are set out in Order HFP/417/2017 of 12 May (BOE of 15 May 2017). It is not just another return: for those in it, it replaces the former forms 340 and 347, and it changes the way the accounts department works.

Who must use it

The rule in Article 62.6 of the VAT Regulation is simple to state: it applies to anyone with a monthly VAT settlement period. In practice, that means three groups:

• Large companies: those whose turnover exceeded €6,010,121.04 in the previous calendar year (Article 71.3 of the VAT Regulation, which refers to Article 121 of the VAT Act).
• Businesses registered in REDEME, the monthly VAT refund register.
• Groups of entities taxed under the special VAT group regime.

Anyone outside these three groups can opt in voluntarily through a census declaration, but bear in mind that the choice has consequences: it means switching to monthly settlement.

Which books and what deadline

This is how four record books are kept: invoices issued, invoices received, capital goods and certain intra-Community transactions.

The deadline is what gives the system its name and what demands the most discipline: four calendar days, excluding Saturdays, Sundays and national public holidays. For invoices issued, it runs from the date of issue; for invoices received, from their entry in the accounts, with a limit of the 16th of the month following the settlement period in which they were included.

How it relates to VeriFactu: they are mutually exclusive

It has been the most common question since VeriFactu was announced, and the answer is short: if you are in the SII, you are outside VeriFactu. That is what Article 3.3 of the Regulation approved by Royal Decree 1007/2023 says: it exempts from those obligations anyone who keeps their record books through the e-office under Article 62.6 of the VAT Regulation.

The logic is clear: the Tax Agency already receives the details of your invoices through the SII, so it does not also need VeriFactu's invoice records. What differs is the purpose of each system: the SII reports transactions for the VAT books; VeriFactu regulates how your software generates and chains the invoice.