Suministro Inmediato de Información (SII) in Spain – Complete Guide
The Suministro Inmediato de Información also known as SII is Spain’s real-time VAT reporting system. It was implemented on July 1, 2017, under Royal Decree 596/2016. The system requires businesses to submit invoice data electronically to the AEAT by using structured XML files instead of filing regular VAT returns.
SII is mandatory for large businesses, VAT groups, and companies registered in REDEME. Other businesses may also choose to join the system voluntarily. It applies to most of Spain, except in regions with separate tax systems such as the Canary Islands, Ceuta, and Melilla.
This blog explains everything a business needs to know about SII in Spain.
What is SII?
The Suministro Inmediato de Información (SII) is a system where businesses submit their VAT invoice data electronically and almost in real time to the AEAT.
Who Must Comply with SII?
- Large companies with an annual turnover exceeding €6,010,121.04
- Businesses registered in the Monthly VAT Refund Registry known as REDEME
- VAT groups
- Other companies that choose to join the system voluntarily and agree to remain for at least one full calendar year
Who Is Not Required to Use SII?
Businesses with an annual turnover below €6,010,121.04
Businesses that file VAT returns on a quarterly basis instead of monthly
Self-employed professionals and sole traders not registered in REDEME
Companies that are not part of a VAT group
Businesses under certain special VAT regimes
Where Is SII Applicable in Spain?
The SII is applicable in specific regions and tax jurisdictions within Spain.
Where SII applies:
- Businesses operating in mainland Spain and the Balearic Islands
- Taxpayers who report VAT to the Spanish State Tax Agency under the national VAT system
Where SII does not apply:
- Businesses located in the Canary Islands, which use a separate tax system called IGIC
- Businesses located in Ceuta and Melilla, which have their own indirect tax system known as IPSI
- Businesses under the Foral tax regimes of the Basque Country or Navarra, unless they also report VAT to the national tax agency
VAT Books Required Under SII
Businesses using SII must submit the following VAT books electronically to the Spanish Tax Agency:
- Book of Issued Invoices
- Book of Received Invoices
- Book of Intra-Community Transactions
- Book of Investment Goods
SII Due Dates in Spain
| Type of Record | Deadline |
| Issued Invoices | Within 4 calendar days from invoice date (8 days if issued by a third party); always before the 16th of the following month |
| Received Invoices | Within 4 calendar days from the date recorded in the accounting system; before the 16th of the following month |
| Intra-Community Transactions | Within 4 calendar days from the date of shipment or receipt |
Investment Goods
| Annually, by January 30 of the following year
|
Note: Weekends and national holidays are excluded from deadline calculations.
Technical Requirements for SII in Spain
- Digital Signature
A business will need a valid electronic certificate that acts as a digital signature to use SII. This certificate is required to confirm the identity of the business or its representative when sending data on the AEAT platform. It will protect the data and make sure the information is original and secure.
The certificate must be issued by a trusted authority that AEAT accepts such as FNMT. It can be linked to a person or to a company. Without this certificate a business will not be able to access SII or send VAT records.
- XML Data Format
A business must prepare invoice data in XML format to use SII. XML is a structured file that allows AEAT to read the information in a standard way. The file must follow the official format given by AEAT which includes specific rules on required fields and structure. Only correctly formatted XML files will be accepted so the business must make sure its system can generate these files as per AEAT’s technical guidelines.
- Submission Methods
A business can send data to AEAT using one of the following methods:
- Web Services (API) – The accounting system connects directly to SII and sends data automatically. This method is best for businesses with high transaction volume.
- Web Portal (Manual Entry) – The business enters data manually on the AEAT website. This method is suitable only for businesses with very few transactions.
How SII Works in Spain
- XML File Creation
A business does not need to send the full invoice but must extract only the required key data fields and then format them into XML files according to the technical specifications of the AEAT.
- Electronic Submission
The XML files are submitted electronically to the AEAT through its official website. Each submission corresponds to a specific VAT book, such as issued invoices, received invoices, or intra-community operations.
- Validation by AEAT
After submission, the AEAT checks the file and returns a status:
- Accepted
- Accepted with errors
- Rejected
Note: If a file is rejected or contains errors, the business must correct the data by submitting a modification record to the AEAT.
4. Real-Time Compliance Monitoring
The AEAT uses the submitted data to pre-fill VAT books. As a result, businesses using SII are exempt from submitting certain tax forms such as Models 347, 340, and 390.
Voluntary Requirements
A business that is not legally required to join SII can still choose to opt in voluntarily.
- Formal Notification – The business must notify AEAT of its decision to join SII through the official procedure.
- One-Year Commitment – Once registered, the business must remain in the SII system for at least one full calendar year.
- Full Compliance – The business must meet all technical and reporting rules of SII the same as mandatory users.
SII Penalties in Spain
If a business does not follow the rules of SII then the Spanish Tax Agency will apply financial penalties based on the type of non-compliance and even a one-day delay can lead to fines which are calculated quarterly with no reduction based on how late the data was submitted.
- Late Submission of Invoices
A fine of 0.5% of the total invoice amount applies for delays in reporting issued or received invoices.
- Minimum fine: €300
- Maximum fine: €6,000 per quarter
- Late Submission of Investment Goods or Intra-Community Records
A fixed penalty applies for delays in these specific VAT books.
- Incorrect, Omitted, or False Data
A penalty of 1% of the incorrect or missing amount applies for inaccurate or false submissions.
- Minimum fine: €150
- Maximum fine: €6,000
- Complete Non-Compliance
If a required business does not report any SII data then a fine of 1% of annual turnover will apply.
- Impact on VAT Deductions
If invoice data is not correctly reported then the business may lose the right to deduct input VAT where mismatches or missing records exist.
- Voluntary Correction
If errors are corrected before the tax agency sends a formal notice or begins an audit then penalties may be reduced or fully waived depending on the case.
Benefits of SII in Spain
- Exemption from Submitting Certain VAT Forms
Businesses using SII are exempt from filing the following VAT forms:
- Faster Error Handling
When invoice data is submitted shortly after it is issued or recorded then errors can be detected and corrected quickly which helps avoid penalties and ensures compliance.
- VAT Refunds
Businesses that use SII provide accurate and timely data so VAT refunds are processed faster which improves cash flow and reduces delays.
Conclusion
Businesses required to use SII must comply with all technical and reporting obligations. For businesses handling a high volume of transactions, it is recommended to use an SII-compliant solution to automate reporting and ensure timely submission to AEAT. SMEs and businesses not covered under SII will fall under the VERIFACTU system. To understand its requirements, you can refer to our VERIFACTU guide.
FAQ
What is SII in Spain?
SII is a real-time VAT reporting system where businesses send invoice data electronically to AEAT using XML files.
Do small businesses need to use SII?
No, SMEs are not required to use SII. They will follow VERIFACTU instead.
What are the deadlines for SII?
Invoices must be reported within 4 days from issue or accounting date, or 8 days if issued by a third party, always before the 16th of the next month.
Can a business join SII voluntarily?
Yes. A business can opt in by notifying AEAT and must remain in the system for one calendar year while meeting all requirements.
What technical setup is needed for SII?
- A valid digital certificate
- XML generation as per AEAT schema
- Submission via AEAT’s web portal or API