NOM-151 (NOM-151-SCFI-2016) is the Mexican Official Standard that establishes requirements for the preservation of data messages and the digitization of documents. It defines how companies must store electronic documents to maintain their legal validity, including the use of timestamps and preservation certificates issued by Certification Service Providers (CSPs).

What is a preservation certificate?

A preservation certificate is an electronic document issued by a Certification Service Provider (CSP) authorized by the Ministry of Economy. It certifies that a digital document has been preserved in its entirety without alterations since a specific date, through a digital timestamp that guarantees the file's integrity and authenticity.

Which employment documents require a NOM-151 preservation certificate?

Documents that require a preservation certificate include: individual employment contracts, agreements to modify employment conditions, payroll receipts (CFDI), administrative records, termination notices, training certificates (DC-3 and DC-4), occupational health and safety documents, and any digitized document that replaces the paper original.

What are the penalties for non-compliance with NOM-151?

Non-compliance with NOM-151 can result in digital documents not being accepted as evidence in legal proceedings or audits. In the labor context, the STPS can impose fines of 50 to 5,000 UMA for documentation irregularities. Additionally, inadequate preservation can affect the tax deductibility of payroll expenses before the SAT.

What Is NOM-151 and How to Comply in 2026: Complete Guide

Q: Who must comply with NOM-151?

Every company in Mexico that generates, sends, receives, or archives electronic documents with legal or tax value must comply with NOM-151. This includes digital employment contracts, electronic payroll receipts (CFDI), digitized employee files, and any document that may be required during an audit by the STPS, IMSS, or SAT.

NOM-151-SCFI-2002 is one of the most important standards in Mexico's regulatory framework for any company that handles digital documents. Published by the Ministry of Economy and updated on various occasions, this standard establishes the requirements that data message preservation systems and document digitization must meet to have full legal validity in Mexico.

For HR and compliance departments, NOM-151 is not optional: it is the legal foundation that determines whether the digital employee files, electronic contracts, and payroll receipts your company stores will have evidentiary value before authorities such as the Junta de Conciliacion y Arbitraje, the SAT, or the IMSS.

What NOM-151 Establishes

NOM-151 originates from Article 49 of Mexico's Codigo de Comercio, which recognizes the validity of data messages as evidence in commercial transactions. The standard defines the technical and operational requirements that Certification Service Providers (CSPs) authorized by the Ministry of Economy must meet to issue data message preservation certificates.

In practical terms, NOM-151 ensures that a digital document:

Has been maintained intact since its creation or digitization, without unauthorized alterations.
Is accessible for subsequent consultation in the same format in which it was generated, sent, or received.
Allows identification of its author or issuer and the exact moment of its creation or preservation through a timestamp.
Has a preservation certificate issued by an authorized CSP that certifies all the above points.

Who Must Comply with NOM-151

NOM-151 compliance is mandatory for any individual or legal entity that conducts commercial transactions in Mexico and wants their digital documents to have evidentiary value. This specifically includes:

Companies with digital employee files: employment contracts, stamped payroll receipts, acknowledgments of internal policies, training certificates, and any document that forms part of the employee's record.
Organizations that use electronic signatures: any company that uses advanced electronic signatures (FIEL/e.firma) or simple electronic signatures for signing employment or commercial documents.
Multinational companies with operations in Mexico: global companies that need to demonstrate to Mexican authorities that their document management systems comply with local regulations.
Any organization subject to audits by the SAT, IMSS, or STPS: where digital documentation with evidentiary value must be presented.

NOM-151 does not distinguish by company size. Both a company with 50 employees and a corporation with over 10,000 must meet the same requirements if they want their digital documents to have legal validity.

Requirements for Digital Document Preservation

The standard establishes a set of technical requirements that preservation systems must meet. These can be grouped into four fundamental pillars:

1. Document Integrity

The system must guarantee that the content of the data message has not been altered since the moment of its creation or digitization. This is achieved by applying cryptographic hash algorithms (such as SHA-256) that generate a unique digital fingerprint of the document. Any modification, no matter how minor, produces a completely different fingerprint and reveals the alteration.

2. Preservation Certificate

A CSP authorized by the Ministry of Economy must issue a certificate that certifies the document's integrity and the exact date of its preservation. This certificate links the document's digital fingerprint with a legally valid timestamp. The list of authorized CSPs can be found on the Ministry of Economy's official website.

3. Accessibility and Availability

Documents must be consultable at any time and reproducible in the format in which they were originally generated. Simply storing files is not enough: the system must allow their viewing, downloading, and, where applicable, faithful printing of the original.

4. Traceability and Auditing

The system must maintain an immutable record of all operations performed on each document: who created it, when it was consulted, whether it was downloaded, and any other interaction. This audit log is essential in case of audits or labor disputes.

Electronic Signatures Under NOM-151

NOM-151 works in conjunction with other provisions of the Codigo de Comercio (Articles 89 to 114) that regulate electronic signatures. In the Mexican labor context, there are two relevant types of signature:

Advanced electronic signature (FIEL/e.firma): issued by the SAT, it uniquely links the signer to the document through a digital certificate. It is the most robust form of electronic signature in Mexico and has the same validity as a handwritten signature.

Simple electronic signature: includes mechanisms such as email, OTP (one-time passwords), biometrics, or click-to-accept. Although it has less evidentiary strength than the advanced signature, NOM-151 allows documents signed this way to have validity as long as they are preserved in compliance with the standard's requirements and the signer's identity can be demonstrated.

For companies, this means that employment contracts, policy acknowledgments, performance evaluations, and other electronically signed documents must be preserved with their corresponding NOM-151 certificate to have standing before any authority.

Penalties for Non-Compliance

Non-compliance with NOM-151 does not generate a specific direct fine, but its practical consequences can be significantly more costly:

Loss of evidentiary value: digital documents that do not comply with the standard will not be accepted as evidence in judicial or administrative proceedings. In a labor lawsuit, this can mean the difference between winning and losing the case.
Risk during tax audits: the SAT can reject digital documentation that does not meet preservation requirements, which can result in fines for tax non-compliance ranging from $1,500 MXN to $38,700 MXN per improperly preserved document, according to the Codigo Fiscal de la Federacion.
Exposure in labor disputes: without valid digital files, the company is left unprotected against employee claims. The costs of adverse judgments can amount to months of the affected worker's salary.
STPS penalties: during Ministry of Labor inspections, inadequate labor documentation can result in fines of 50 to 5,000 UMAs (between $5,428 MXN and $542,850 MXN in 2026).

How to Implement NOM-151 Compliance

Complying with NOM-151 requires a combination of adequate technology, well-defined processes, and a reliable technology partner. Here are the recommended steps:

Audit your current situation: identify all employment documents your company generates, receives, and preserves in digital format. Determine which ones require a preservation certificate.
Select an authorized CSP: verify that the certification service provider is registered with the Ministry of Economy and operates under the standard's parameters.
Implement a document management platform: adopt a system that automates the generation of preservation certificates, electronic signatures, and secure document storage.
Train your HR and compliance team: ensure that responsible staff understand the standard's requirements and internal compliance processes.
Establish document retention policies: define retention periods aligned with Mexican labor and tax legislation (generally 5 years for employment documents and up to 10 years for tax documents).

The Role of Technology in Compliance

The complexity of NOM-151 makes manual compliance virtually unfeasible for mid-size and large companies. Platforms like Rokisoft automate the entire lifecycle of the digital employment document: from creation and electronic signature to automatic generation of NOM-151 preservation certificates, through secure storage with full traceability.

Companies like Ford, Oracle, and Bachoco, with combined workforces exceeding 40,000 employees, use this type of solution to manage hundreds of thousands of employment documents per year without relying on error-prone manual processes. Automation not only ensures regulatory compliance but also significantly reduces document management time and the costs associated with physical storage.

When evaluating a technology solution for NOM-151 compliance, it is important to verify that it offers: integration with authorized CSPs, support for multiple types of electronic signatures, an immutable audit trail, encrypted storage with redundancy, and the ability to generate complete employee files that can be presented as evidence before any Mexican authority.

Conclusions

NOM-151 is the regulatory cornerstone of digital documentation in Mexico. In an environment where the digitization of HR processes is advancing rapidly, complying with this standard is not just a legal obligation but an operational advantage that protects the company against labor, tax, and legal risks.

Organizations that implement document management systems with built-in NOM-151 compliance are better prepared for audits, labor lawsuits, and the complete transition to digital employee files with full legal standing.