Certified digitization: converting paper documents to digital

In the era of digital transformation, the concept of the "paperless office" has become a strategic necessity. But for a company to securely and legally dispose of its physical files, it needs a process that ensures that digital copies have the same validity as their paper originals. This is what we call certified digitization.

Certified digitization is a legal and technological framework regulated by the Spanish Tax Agency (AEAT), which allows organizations to convert invoices, contracts, delivery notes, and other critical documents into unalterable and authentic digital files. This change not only frees up physical space, but also provides unprecedented levels of efficiency and security.

In this article, we will analyze in detail what certified digitization is, how it works, what its benefits are, the legal framework that regulates it, the technical requirements it must meet, and how to implement it in your company to comply with regulations.

What is Certified Digitization and Why is it Important?

Certified digitization is the process of converting paper documents into digital format while guaranteeing their authenticity, integrity, and inalterability, so that the electronic versions are legally equivalent to the physical originals. It is not a matter of creating a reference copy, but rather of generating a legally recognized substitute for the physical document. 

The key to this process lies in its ability to guarantee the integrity and authenticity of the digital copy through the use of cryptographic mechanisms, such as advanced electronic signatures, and the use of software approved by AEAT. To do this, technologies owned by trusted service providers registered in the European Union and other equivalent bodies are used to certify this process.

It is this guarantee of inalterability that gives the process its main strategic value: the ability to proceed with the legal destruction of the original paper document.

In Spain, this procedure is mainly regulated by Order EHA/962/2007, of April 10, and the Resolution of October 24, 2007, of the AEAT, which establish the requirements that the systems and software used must meet.

Legal Basis and Difference From Scanning

The difference between a scanned document and a certified digitized copy is enormous from a legal perspective. A simple scan generates a digital image with no intrinsic probative value. In contrast, a certified digitized copy is a legal construct whose validity stems from strict compliance with a process defined by Spanish and European legislation.

The legal pillars holding up this process are:

• Order EHA/962/2007: the founding regulation that specifically defines and regulates the process for the certified digitization of invoices and substitute documents. It defines the process as "the obtaining of a faithful and complete digital image of the original paper document to be replaced".
• Law 39/2015 and Law 40/2015: these laws establish the general framework for administrative procedure and the legal regime of the public sector, recognizing and regulating the use of electronic signatures as a mechanism to guarantee integrity and authenticity in electronic interactions.

Benefits of Certified Digitization: Costs, Efficiency, and Compliance

The adoption of a certified digitization system has a positive and measurable impact on multiple areas of the company:

• Direct and Indirect Cost Savings: the most immediate advantage is the drastic reduction in the need for physical storage space, eliminating the costs associated with filing or renting premises, in addition to savings on consumables such as paper and ink. Indirectly, there are significant savings in working hours, as employees no longer have to spend time on tasks such as filing.
• Exponential Increase in Efficiency and Productivity: being able to retrieve any document in seconds through intelligent searches transforms workflows. This agility is multiplied when the system is integrated with the company's accounting software or ERP, automating processes such as invoice accounting.
• Enhanced Security and Regulatory Compliance: the process ensures compliance with AEAT regulations. It mitigates the risk of loss or damage to critical documents due to incidents such as fires, floods, or simple misplacement. In cybersecurity, the use of electronic signatures and cryptographic seals prevents unauthorized modification of documents, creating a tamper-proof digital archive.  
• Improved Strategic Decision-making: instant access to accurate and reliable financial and operational information enables managers to make faster and  more informed  decisions.

The cumulative effect of these benefits is a source of competitive advantage by providing the organization with greater operational agility. These savings allow for the reallocation of resources from repetitive administrative tasks to higher-value activities, such as data analysis or financial planning. 

The result is a company that can react more quickly to market changes, close its books faster, and streamline processes such as customer onboarding.

The Process of Certified Digitization: Steps to Ensure Legal Validity

An approved certified digitization process follows an uninterrupted and auditable sequence of phases, where technology guarantees integrity at every stage. Advanced tools such as Tecalis solutions automate this flow to offer maximum efficiency and security:

1. Image Capture: the first step is to obtain a high-quality digital image of the paper document. This is done using scanners that comply with the resolution and quality standards defined by the regulations.
2. Data Processing and Extraction (OCR - Optical Character Recognition): once the image has been captured, the approved software processes it. Technologies such as OCR play a key role. Tools such as Tecalis OCR analyze the image and automatically extract key data from the document (tax ID number, invoice number, date, etc.), minimizing manual data entry and associated errors.  
3. Metadata Generation and Indexed File: the system uses the extracted data to generate a set of structured metadata. This "index file" must contain all the mandatory fields required by tax and accounting regulations. 
4. Application of Electronic Signature and Time Stamp: the crucial step that "certifies" the document. An advanced electronic signature is applied to the digital image and its associated metadata. This signature acts as a cryptographic seal that guarantees two fundamental principles: authenticity (who performed the process) and integrity (it has not been modified). Simultaneously, a qualified time stamp is applied to certify the exact moment when the digitization was performed.
5. Secure Storage and Document Management: the digital file, together with its signature and metadata, is stored in a secure and organized document database. Solutions such as Tecalis Sign not only manage the signing process, but also act as a secure digital archive, allowing the custody, management, and consultation of documents with full legal guarantees and complete traceability of all actions performed on them.

Software Requirements With AEAT Approval

In order for software to be used in a certified digitization process, it must obtain AEAT approval. This process verifies that the tool complies with the specific technical specifications detailed in the Resolution of October 24, 2007.

The requirements include:

• Image Quality and Standard Formats: the software must guarantee a minimum resolution to ensure that the copy is faithful and complete. In addition, only standard file formats that ensure interoperability and long-term preservation, such as ISO 19005 (PDF/A), PNG, or PDF 1.4, are permitted. 
• Advanced Electronic Signature: an advanced or qualified electronic signature, based on a recognized digital certificate, must be incorporated to seal each digitized document.
• Digital Fingerprint (hashing): at a technical level, integrity is guaranteed by hash functions. A unique "digital fingerprint" is created for each file. Any minor alteration to the document would produce a completely different fingerprint.
• Structured Document Database: the system must organize the documents in a database that allows full  access, online consultation, and selective searching by any of the mandatory data fields in the invoice logbooks.  
• Formal Approval Process: the software developer must submit a formal application to the AEAT that includes a responsible statement, a technical description, and an audit report issued by an independent entity certifying that the software complies with all regulatory requirements.

With the use of fingerprint, certification, and electronic signature technologies such as Tecalis Sign, certified digitization systems can perform this process with full legal validity.

The AEAT maintains a public list of approved certified digitization software. This gives companies the peace of mind that, if they use one of these solutions, they will be complying with the regulations. Suppliers such as Tecalis have approvals and constant updates to adapt to regulatory changes.

Mandatory: Legal and Secure Destruction of The Original Paper Document

One of the most important aspects of certified digitization is that it enables the destruction of physical documents. This step must be carried out in a controlled and documented manner to avoid legal risks.

The AEAT requires that, once it has been verified that the digital document meets the requirements of integrity and authenticity, the original paper document be destroyed to avoid duplication and fraud. 

The aim is to ensure that there is only one valid copy, avoiding confusion in audits and ensuring that the digital copy is the only document with probative value.

Most Common Use Cases by Sector: Invoices, Delivery Notes, Payroll, etc.

The application of certified digitization spans multiple departments and processes, demonstrating its versatility and ability to solve critical business problems:

• Finance and Accounting Department: this is the main area. Certified digitization of supplier invoices allows them to be imported and automatically accounted for in ERP systems, the management of tickets and receipts for expense reports, and the legal archiving of sales invoices issued.  
• Logistics and Supply Chain: the digitization of delivery notes or delivery slips is a high-impact use case. A carrier can collect the handwritten signature on the paper delivery note, digitize it in a certified manner on the spot, and transmit it to headquarters.  
• Human Resources: certified digitization of employment contracts, signed pay slips, sick leave forms, employee onboarding, and other employee file documents ensures secure, confidential archiving that complies with data protection and labor  regulations.  
• Legal and Purchasing Department: converting signed contracts, confidentiality agreements, purchase orders, and other legal documents to a certified digital format ensures their long-term preservation and facilitates their quick retrieval in the event of litigation or an audit.  
• Healthcare Sector: with extremely strict regulations, the certified digitization of medical records, informed consents, and administrative documentation ensures the integrity, confidentiality, and quick access to patient information.  

The common thread linking all these use cases is that they apply to "record documents": those that have intrinsic value and require the highest level of trust and auditability. It is not a question of digitizing general correspondence, but of protecting documents that serve as proof of a transaction, an obligation, or a right.

How to Integrate Certified Digitization Into Your Company's Processes

Certified digitization reaches its full potential when it ceases to be an isolated file and is fully integrated into the company's technological ecosystem, primarily with Enterprise Resource Planning (ERP) and Document Management and Processing (DMS) systems.

• Integration With ERP: a certified digitization system must communicate natively with the company's ERP. This connection allows, for example, when digitizing a supplier invoice, the data extracted by the OCR to be sent directly to the ERP accounting module for validation and payment. This enables the automation of complex processes without human intervention. 
• Integration With DMS: the process acts as a secure and legal gateway to a broader document management system. Tools such as Tecalis Sign not only function as a platform for electronic signatures, but also as a high-security digital archive. Acting as a Trusted Third Party, these platforms allow digitized and certified documents to be stored, managing their lifecycle, controlling access permissions, and maintaining a complete audit trail of each query or action.  

The integration of these systems creates a single source of truth for company data and documents. It transforms digitization into a real-time business intelligence engine. When invoice data is captured, certified, and entered into the ERP almost instantly, the company's financial overview is updated by the minute. Financial planning is no longer based on month-end reports but on live, accurate data.

Who Can Digitize and What Requirements Must The Company Meet?

The regulations establish that the certified digitization process can be carried out by two main actors: the taxpayer (the company) or a service provider such as Tecalis. Regardless of the option chosen, what must be clear is that the essential requirement for the EU and the AEAT is to have software that is duly approved for the process.

Opting for a specialized service provider such as Tecalis offers significant advantages, as it takes on the burden of acquiring and maintaining the approved software, managing the technological infrastructure, keeping up to date with regulatory changes, and ensuring that the process is carried out with the highest quality and security, freeing the company from this complex responsibility.  

Within the ecosystem of providers, there is a category that offers the highest level of legal certainty and trust: the QTSP or Qualified Trust Service Provider.

A QTSP is a natural or legal person who has been certified by a national supervisory body to provide qualified trust services under the strict framework of Regulation (EU) No. 910/2014, known as eIDAS. This regulation creates a common European framework for electronic identification and trust services, ensuring that they operate securely, reliably, and with full legal recognition in all EU member states.  

The services offered by a QTSP, such as Tecalis, include:

• Issuance of qualified certificates for electronic signatures and seals.
• Qualified signature and seal validation services.
• Qualified time-stamping services.
• Qualified services for the preservation of electronic signatures, seals, and documents.  

Order EHA/962/2007 and Other Regulatory Frameworks

As mentioned above, this is the legal basis for certified digitization in Spain, regulating both the conditions for document preservation and software requirements.

At the European level, the eIDAS Regulation (910/2014) establishes the framework for electronic signatures, digital seals, and trust services. In Spain, Law 6/2020 adapts eIDAS to domestic law and reinforces the legal certainty of these processes.

Is it The Same as Verifactu? Clarifying Concepts

A common question is whether certified digitization is the same as Verifactu, the invoicing system that will become mandatory in Spain. The answer is no; they are complementary but different concepts.

While Verifactu focuses on issuing invoices in real time, ensuring that the billing records sent to the AEAT are accurate and unalterable, certified digitization focuses on the preservation and replacement of paper documents with digital copies.

In conclusion, certified digitization is a strategic requirement for companies that want to comply with regulations, gain efficiency, and move towards a paperless office.

Adopting advanced technological solutions, such as those offered by Tecalis, allows companies to digitize their invoices, delivery notes, payrolls, and contracts in a certified manner, electronically seal each document, and eliminate paper with legal peace of mind.

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