Tax audit and investigation actions, including judicial assistance actions in which Tax Agency personnel participate, must be adapted to the situation of the economic sectors to which they are directed. In recent years, economic activities have been characterized by their high level of computerization.

This evolution is confirmed in the indicators on the use of information and communication technologies in companies published by the National Institute of Statistics such that, in the years 2020 and 2021, 99.26% of companies with more than 10 workers had computer (this percentage was 85.20% in companies with less than 10 workers). The high degree of computerization of citizens brings with it other collateral effects that condition the proper development of the tax verification and investigation activity that is carried out in a traditional way. On the one hand, the volume of information available increases significantly, so that it becomes difficult to discriminate what information is available on the electronic device that may be relevant from a tax point of view; In many cases, not even companies have a precise idea of the volume of data they have on their computers. On the other hand, the location of the information can be found anywhere in the world , as a consequence of the fact that the information can be located remotely or "in the cloud", so its investigation may require the use of specific methods. Finally, it should be highlighted the existence, in some computer systems, of applications or utilities that allow tax evasion or fraud so that , at will of the interested party or third parties, the true economic and tax reality of the taxpayers is hidden, omitting and altering real data or interpolating and adding fictitious data (known as dual-use software) .

To facilitate the actions carried out by the Tax Agency, in relation to the difficulties highlighted in the previous paragraph, the Inspection Department has powers to directly carry out computer audit functions derived from inspection actions or judicial assistance and coordination. of the units specialized in this matter, as well as the issuance of reports on electronic billing. For this purpose, in 2007 the Central Computer Audit Unit (UCAI) was created which, since November 2008, has been part of the National Fraud Investigation Office.

Among the functions performed by the UCAI, the following stand out:

1. Support to Inspection Teams and Units in their inspection actions, fundamentally in the acquisition of documentation when it is in computerized media.

2. Analysis and verification of computer systems and equipment through which the management of economic activity is carried out, in whole or in part, and obtaining data from them for subsequent examination.

In any case, the information obtained is ensured regarding its integrity and authenticity by obtaining the digital fingerprint.

According to the description of these functions, the UCAI participates in inspection actions , judicial dumping of data (on those occasions in which it is necessary to seize digital media to subsequently recover the information) , preparation of reports, creation of virtual machines to reproduce the work environments of the investigated, solving problems with encrypted files, among other issues, in order to obtain a complete image of the real economic activity of the taxpayers.

Another of the UCAI's functions is to incorporate the data it has obtained in the different operations in which it intervenes to the different existing computer platforms for use and analysis by the Inspection. It also carries out this task in relation to the devices whose custody is in charge or is provided by the Security Forces to the National Fraud Investigation Office.

It is also responsible for complying with the requirements made by courts or tribunals of the operations in which the Tax Agency has intervened when a computer audit has been carried out. Among these requirements can be found the expurgation of what has been previously provided in the procedure, or making a complete or partial copy of what is kept both in our headquarters and in the judicial headquarters, or making a list and return of seized effects, or identification and classification of the documentation contained in an operation.

On the other hand, expert-type actions are also carried out . For example, information on software valuation in foreign operations or reporting on technological innovation in projects carried out by entities that have applied a deduction for research and development expenses.

Finally, another of the UCAI's tasks is to train the different territorial computer audit units (UAI) . These Units are intended to provide computer audit support to the remaining Teams and Units of the Regional Inspection Unit in their inspection actions.

As a sign of their important participation in the mission of the Tax Agency, that is, the application of the tax and customs system, in 2021 the Computer Audit Units participated as support in eight out of ten actions of entries and records carried out by the tax and customs inspection bodies. The files of inspection actions with the participation of the UAI completed in 2021 gave rise to the regularization, including sanctions, of 173 million euros.