The Immediate Supply of Information (SII) is a more agile and modern procedure for telematic bookkeeping system for VAT.

Through the Electronic Headquarters of the Tax Agency (AEAT), companies will have to provide billing records (not invoices) electronically.

With this information, the AEAT will configure, in real time, the different Registry Books.


As of July 1, 2017, a total of 62,000 companies are required to supply their billing records electronically.

New features and updates have been incorporated every year and a new update is planned for January 2021.


  • Large companies with an annual turnover of more than 6 million euros.
  • Companies registered in the REDEME (Monthly VAT Refund Regime).
  • SMEs and the self-employed who pay taxes under the special VAT group regime.
  • Completely optional, any other taxpayer who does not meet the above requirements will be able to benefit from the new system.


  • You will have more time to present the periodic self-assessments, you will have 10 additional days.
  • It will no longer be necessary to present the 340347 and 390 forms.
  • You will have fewer information requirements from the AEAT since now they will have in detail the content of the invoices.
  •  Errors will be avoided since the Electronic Office will have the fiscal data of each company to be able to make a draft of VAT and facilitate its declaration.

Transform the change into an opportunity to improve the management of your business

    1. Check if you are obliged to manage your VAT registration books.
    2. Keep your accounting up to date and start registering invoices in a shorter period of time.
    3. Train yourself in advance to learn about this new management mode in detail.
    4. Even if you are not obliged, you can choose to voluntarily join the SII, thus being exonerated from presenting forms 340, 347 and 390.
    5. Check with your software provider if your billing and/or accounting solution is adapted to the change.

Explore our solutions for the management and administration of your Finances and find the one that best suits your needs.

Axional FI


Learn step by step how our Axional FI-SII  system works.

1. Issuance and registration of invoices

Sales bills are issued and purchase bills are registered in the accounting / ERP system following the usual procedures.

The posting of customer/vendor invoices is done following current processes.

2. Axional FI-SII

The new Axional FI-SII module performs a mapping of invoices and tax records to convert the data into the format that the AEAT needs.

It manages at all times the invoices declared, those pending of declaration, the status of the submission and the responses to the information, controlling the traceability of the modification procedures and data cancelation. More information on Axional FI-SII de Axional FI-SII.

3. Submission to the AEAT

Once the conversion is made, it is submitted to the AEAT Electronic Headquarters.

Once verified, the entity will return the data sent with one of the following states:

  • Full acceptance.
  • Partial acceptance.
  • Complete rejection.


Discover the most common questions

The Immediate Supply of Information (SII) is a new system for keeping the Value Added Tax register books through the AEAT Electronic Headquarters, by means of the quasi-immediate supply of billing records. In this way, the new SII makes it possible to bring the moment of registration or accounting of the bills closer to the effective performance of the economic operation that underlies them.

The SII is applicable as of July 1, 2017, on a mandatory basis, to taxpayers who currently have the obligation to self-assess VAT on a monthly basis (about 63,000 obligated):

  • Large Companies (turnover of more than 6 million euros).
  • VAT groups.
  • Registered in the REDEME (Monthly VAT Refund Regime).
  • Taxpayers who voluntarily decide to use the new system.

Yes. There will be the option to benefit from the system for those taxpayers who want to profit from its advantages, even if they do not meet the necessary requirements to be obliged.

The main one is that the companies’ billing records, as well as the declaration of other operations, will have to be made electronically and immediately at the AEAT electronic headquarters.

You will have to check whether or not you are obliged to electronically manage your VAT registration books. If so, keep your accounting up to date and always have your invoices well recorded with good accounting software. In addition, it will be convenient for you to train in time to know in detail this new VAT telematic management system.

It should be taken into account that the SII will have a repository of record books to instantly associate the information of the invoices received with those issued 340347 y 390. The verification of the data will be faster, since the Tax Agency will obtain the information in real time. You will save time since you will not have to keep a record book with your data, since this will be updated in the AEAT with the information that the taxpayer will provide. In addition, there will be fewer errors since, with these tax data, the AEAT will create a kind of “VAT draft” that companies will receive.

*Campos obligatorios.