The precautionary measures within the inspection procedure, as provided in article 146 of Law 58/2003, General Tax, of December 17 (hereinafter LGT), are intended to prevent the disappearance, destruction or alteration of the decisive evidence of the existence or compliance of tax obligations or that their existence or display is subsequently denied, said measures having to meet a series of conditions. Thus it is established that:

• They must be proportionate to the purpose they pursue, adopting the measure that causes the least damage to the taxpayer, as long as it is sufficient to secure the element of proof in question.

• They cannot be extended indefinitely during the entire processing and resolution of the inspection procedure, since they are temporarily limited to the indicated purposes.

• Measures that may cause damage to the taxpayer that is difficult or impossible to repair cannot be adopted.

The measures may consist of the sealing, deposit or seizure of the goods or products subject to tax, as well as books, records, documents, files, premises or electronic data processing equipment that may contain the information that is intended to be secured. In article 181.1 of the general regulation of actions and procedures for tax management and inspection and for the development of common standards for tax application procedures, approved by Royal Decree 1065/2007, of July 27 (hereinafter RGAT ), these measures are developed.

The seal is carried out by means of sealed ligation or by any other means that allows the closing or tying of books, records, electronic equipment, envelopes, packages, drawers, doors of rooms or premises or others elements of evidence, so that they are not opened without the authorization and control of the Inspection bodies.

The deposit consists of placing the evidence in the custody or custody of the natural or legal person determined by the Administration. Documents or objects deposited may be previously sealed.

The seizure consists of the taking possession of movable evidence by the officials of the Inspection. Seized documents or objects may also be previously sealed.

The precautionary measures adopted within an inspection procedure, in accordance with the provisions of article 146 LGT and 181.4 RGAT, must comply with a series of requirements. This is how they should be:

• Reasoned, with expression of the circumstances and purpose that determine the need to adopt said measure in order to secure the element of evidence in question.

• Ratified within 15 days following its adoption by the Chief Inspector.

• Documented in the corresponding diligence in which the circumstances and purpose that determine its adoption, the type of precautionary measure and inventory of the merchandise, documents or other elements that it affects must be stated. Likewise, the taxpayer must be informed of his or her right to make allegations within a period of 5 days.

• Lifted if the circumstances that motivated the adoption of the precautionary measure disappear.

The breach of precautionary measures constitutes an infraction of resistance, obstruction, excuse or refusal to the actions of the Tax Administration, the sanction of which, in accordance with the provisions of article 203.8 of the LGT, consists of a fine of 2% of the turnover of the offender with a minimum of 3,000 euros.

After the adoption of precautionary measures, the chain of custody of the evidence must be ensured, since the guarantee of said chain, although it does not have a specific treatment in the tax regulations as it is the object of analysis, fundamentally, in the criminal field, must It should also be ensured in the inspection procedure, as occurs with any administrative procedure to which its application is appropriate.

The chain of custody of the evidence obtained after the adoption of precautionary measures accredits the way in which the tasks of collection, transfer, manipulation and storage of the objects of evidence until their analysis were carried out, so that the identity between them is guaranteed. the object initially obtained (sealed, deposited, seized, etc.) and the one finally investigated and reported. To do this, it is necessary to document the various stages through which the objects of the test have passed, so that there is a record of all the activities carried out by each of the people who come into contact with the evidence, thus ensuring the traceability of the evidence obtained.

The chain of custody constitutes a guarantee that the evidence analyzed is the same as that collected during the investigation, so that there are no doubts about the purpose of said evidence. The integrity of said chain of custody allows us to prove that the evidence obtained in the procedure has been preserved completely and adequately, and has not been altered either intentionally or accidentally. In this way, the evidence provided to the procedure has all the guarantees and ensures respect for the right to the presumption of innocence and the right to a fair trial with all guarantees.

The violation of the chain of custody affects what is called the plausibility of the expert evidence and, consequently, its legitimacy and validity to serve as prosecution evidence in the process. In the event that such a chain of custody is broken, given the instrumental nature of this guarantee, this result has the effect of expelling the evidentiary inventory due to the doubt that it was the same, although this does not prevent, through other evidence, certainty of the existence of such evidence can be reached.