Also known as: FIEL, Advanced Electronic Signature, FEA
A digital certificate issued by Mexico's SAT that identifies individuals and entities, used to electronically sign documents with legal validity.
The e.firma (formerly known as FIEL — Firma Electrónica Avanzada) is a set of digital data and files issued by Mexico's Tax Administration Service (SAT) that uniquely identifies an individual or legal entity. It consists of three elements: a digital certificate (.cer file), a private key (.key file), and an access password. It carries the same legal validity as a handwritten signature.
The e.firma identifies the person or entity and is used to sign legal proceedings, tax returns, and government documents. The sello digital is a certificate derived from the e.firma used for specific operations like electronic invoicing (CFDI) or VUCEM filings. One entity can have multiple digital seals but only one e.firma.
In customs operations, the e.firma is essential for signing electronic pedimentos, conducting filings in VUCEM (Mexico's Single Window for Foreign Trade), enrolling in the Padrón de Importadores (Importer Registry), and — starting June 2026 — for importers to sign the MVE (Electronic Valuation Declaration). This last point is critical: the MVE mandatorily requires the importer's own e.firma, not the customs broker's.
Starting June 1, 2026, the Electronic Valuation Declaration (MVE) becomes mandatory. The importer MUST sign it with their own e.firma. The customs broker's digital seals DO NOT work for signing the MVE. Every importer needs a valid e.firma and a process for digital signing.
Stay MVE compliant
Learn more→Digital Seal
An electronic certificate linked to the e.firma used to authenticate and sign documents with VUCEM and other SAT systems.
RegulationsVUCEM (Single Window)
Mexican government's electronic platform that centralizes all foreign trade procedures in a single digital window.
RegulationsElectronic Validation Desk (MVE)
Mandatory process where importers electronically validate and sign merchandise value information before customs clearance.
CustomsCustoms Declaration (Pedimento)
The official document filed with Mexican customs that covers the entry or exit of goods from Mexico, prepared and submitted by a licensed customs broker.
