Complete guide to Mexico CFDI 4.0 electronic invoicing compliance including SAT validation, UUID folio fiscal requirements, and PAC provider integration.
Mexico implemented mandatory electronic invoicing through the CFDI system managed by the Servicio de Administracion Tributaria. CFDI stands for Comprobante Fiscal Digital por Internet and serves as the digital tax receipt for all commercial transactions in Mexico.
Version 4.0 of CFDI launched in January 2023 with enhanced validation rules, expanded tax regime codes, and stricter data requirements. All taxpayers must generate CFDI invoices through authorized PAC providers who digitally stamp invoices with UUID identifiers after SAT validation.
The system covers B2B and B2C transactions with mandatory real-time validation before invoice issuance. Every CFDI must contain RFC tax identification numbers for both issuer and recipient, detailed product or service descriptions using SAT catalog codes, and complete tax breakdown by type and rate.
Version 4.0 requires precise tax regime codes matching SAT registry. Issuer and recipient regimes must align with allowed transaction types. Mismatched regimes cause validation rejection.
Export invoices require detailed customs and logistics data including incoterms, certificate numbers, and destination country codes. Domestic invoices must explicitly declare non-export status.
Foreign recipients without Mexican RFC must use the generic global RFC code. Proper formatting follows strict patterns or validation fails during PAC stamping process.
SAT product and service catalog expanded with thousands of new codes. Each line item must reference valid catalog code matching product description. Generic codes eliminated for specific categories.
Every CFDI receives a UUID Folio Fiscal after successful validation by a PAC provider. The UUID is a unique 36-character identifier that serves as the legal proof of invoice authenticity and SAT registration. Invoices without valid UUID are not legally recognized for tax purposes.
The digital stamp process involves submitting the CFDI XML to the PAC who validates structure and content against SAT rules. If validation passes, the PAC applies a digital signature certificate and generates the UUID. The stamped invoice is returned to the issuer with the UUID embedded.
The UUID must appear on all invoice representations including printed or PDF copies. Recipients verify UUID authenticity by querying SAT validation services. Duplicate UUID generation is prevented by the PAC system which tracks all issued identifiers.
PAC stands for Proveedor Autorizado de Certificacion. These are private companies authorized by SAT to digitally stamp CFDI invoices on behalf of taxpayers. All CFDI must pass through a PAC for validation and UUID generation before being issued to customers.
Businesses contract with PAC providers for stamping services. Integration typically occurs via web services API where the business system submits CFDI XML and receives back the stamped version with UUID. PACs charge per-stamp fees and provide technical support for validation issues.
PAC providers maintain redundant infrastructure to ensure high availability. If one PAC experiences downtime, businesses can failover to backup PAC connections to maintain invoice issuance continuity. Response times for stamping are typically under 2 seconds.
The RFC is Mexico tax identification number required for all CFDI parties. Issuers and recipients must have valid RFC codes registered with SAT. For Mexican entities this is their official tax ID. For foreign entities without Mexican tax registration, the generic global RFC code is used.
RFC format follows strict patterns with length and character validation. Individual RFC contains 13 characters while corporate RFC contains 12 characters. The global RFC for foreign entities is a standardized code indicating non-Mexican tax residence.
SAT validates RFC codes during CFDI processing. Invalid or inactive RFC codes cause immediate rejection. Businesses must ensure customer RFC data is current and formatted correctly before invoice generation to avoid validation failures.
CFDI cancellation follows strict rules. Invoices can be cancelled within specific timeframes depending on recipient acknowledgment. The issuer submits cancellation request through PAC which records the cancellation in SAT systems with reasons and timestamps.
For invoices with amounts exceeding threshold limits, recipient acknowledgment is required before cancellation completes. The recipient has a defined period to accept or reject the cancellation request. Unreported cancellations within time limits are automatically processed.
Amendments are handled by cancelling the original CFDI and issuing a new corrected version. Direct modification of issued CFDI is not permitted. The replacement CFDI must reference the cancelled UUID to maintain audit trail and explain the correction reason.