Factura 4.0: A Guide for Businesses

What Is a "Factura 4.0"?

When people in Mexico refer to a Factura 4.0, they mean an electronic invoice issued under the CFDI 4.0 schema (Comprobante Fiscal Digital por Internet, version 4.0) — the current electronic invoicing standard published by Mexico's tax authority, the Servicio de Administración Tributaria (SAT).

"Factura 4.0" is not an official SAT designation; it is the colloquial label that the business and accounting community adopted to distinguish invoices issued under the new schema from those issued under the previous version (CFDI 3.3). In practice, any valid electronic invoice in Mexico since 2023 is a Factura 4.0.

For a primer on the underlying technical concept, see What Is a CFDI?.

Why It Became Mandatory

The migration to CFDI 4.0 was driven by three SAT tax-policy objectives:

Fighting tax evasion by tightening validation of the recipient's identity within the invoice.
Improving traceability of commercial transactions between taxpayers.
Reducing the use of fraudulent invoices through real-time cross-validation of taxpayer data against the Registro Federal de Contribuyentes (RFC) registry.

The SAT established a coexistence period during which both version 3.3 and version 4.0 were accepted, but from 2023 onward version 4.0 is the only valid schema for the general taxpayer population. Issuing or accepting a CFDI in version 3.3 after that deadline has no fiscal effect.

For a full breakdown of every technical change introduced in version 4.0, see our post CFDI 4.0: What Changed and How It Affects Your Business.

Required Fields for a Valid Factura 4.0

One of the most significant changes in CFDI 4.0 is that the recipient's data is now validated against the SAT registry before the Authorized Certification Provider (PAC) stamps the invoice. If any field does not match exactly, the document is rejected.

A valid Factura 4.0 must include the following data:

From the Issuer

Issuer RFC: must be active and in good standing with the SAT.
Issuer name or business name: exactly as it appears in the RFC registry.
Issuer tax regime: the regime under which the issuer operates (for example, 601 – General de Ley Personas Morales; 612 – Personas Físicas con Actividades Empresariales y Profesionales).
Issuer fiscal address postal code: the postal code registered with the SAT — not a branch address or delivery address.

From the Recipient

Recipient RFC: mandatory. For sales to the general public, the generic RFC XAXX010101000 is used; for foreign recipients, XEXX010101000.
Recipient name or business name: must be written exactly as it appears in the SAT registry, including capitalization, accent marks, and punctuation. An abbreviation or variation will cause a rejection.
Recipient tax regime: the recipient must provide the regime under which they are registered (for example, 605 – Sueldos y Salarios; 626 – Régimen Simplificado de Confianza).
Recipient fiscal address postal code: the postal code the recipient has on file with the SAT — not a branch or delivery address.
CFDI use code: the code indicating the purpose for which the recipient will use the invoice (for example, G03 – General Expenses; G01 – Acquisition of Merchandise; P01 – To Be Defined). The SAT validates that the declared use is compatible with the recipient's tax regime.

On the Document Itself

Invoice type: Income (I), Expense (E), Transfer (T), Payment (P), or Payroll (N).
Payment method and payment form: PUE (single payment) or PPD (payment in installments or deferred), plus the payment form code (01 – Cash; 03 – Electronic funds transfer; 04 – Credit card, etc.).
Currency and exchange rate: if the transaction is in a foreign currency, the exchange rate for the day must be stated.
Line items: description, SAT product or service catalog key, unit key, quantity, unit price, and subtotal.
Transferred and withheld taxes: VAT (IVA), income tax (ISR), and special taxes (IEPS) as applicable, calculated at the line-item level.

Ways to Issue a Factura 4.0

There are three paths for a taxpayer to issue a Factura 4.0:

1. SAT Portal (Factura Fácil)

The SAT provides a free tool called Factura Fácil on its portal. This is the most accessible option for taxpayers with low invoice volumes. Its limitation is that the process is entirely manual: the user enters each field by hand, which increases the risk of data-entry errors and becomes impractical at medium or high volumes.

2. Invoicing Software Through a PAC

Most businesses use an invoicing system — an ERP, accounting software, or dedicated invoicing application — that connects to a PAC (Proveedor Autorizado de Certificación, or Authorized Certification Provider). The PAC validates the CFDI, attaches the Timbre Fiscal Digital (TFD, the digital stamp), and transmits the document to the SAT. The issuer receives the stamped XML and a corresponding PDF.

PACs are authorized and regulated by the SAT. The choice of PAC is independent of the invoicing software; many systems come with built-in integration for one or more PACs.

3. API Integration (Programmatic Invoicing)

For businesses with high invoice volumes or those that need to issue invoices as part of an automated workflow — e-commerce platforms, service platforms, or proprietary ERPs — the most efficient approach is a direct API integration with a PAC. The business system builds the CFDI XML in the required XSD format, sends it to the PAC via an API call, and receives the stamped XML in response, with no manual intervention.

This method allows invoices to be issued, canceled, and queried in real time and can be integrated into any system that handles business logic.

Common Rejection Causes

The stricter validations in CFDI 4.0 raised the rejection rate compared to version 3.3. The most frequent causes are:

Incorrect recipient name: a single wrong letter, a missing accent, or an unauthorized abbreviation is enough for the PAC to reject the stamp request.
Incompatible tax regime: the declared CFDI use code is not compatible with the recipient's tax regime according to the SAT catalog.
Wrong fiscal address postal code: the client provides the postal code of their office or delivery address instead of the one registered with the SAT.
Inactive or canceled recipient RFC: the recipient's RFC is not active in the SAT registry.
Incorrect product/service or unit key: the SAT catalog key does not correspond to the description of the invoiced item or service.
Tax calculation errors: VAT calculated on the wrong base, or required withholdings omitted.

How Companies Automate Invoice Issuance

The greatest operational challenge of the Factura 4.0 is not technical but rather a data challenge: obtaining the recipient's exact information — name, RFC, tax regime, fiscal postal code, and CFDI use — with the precision the SAT requires.

Companies handling medium to high volumes typically implement one or more of the following strategies:

Recipient onboarding form: when adding a new client or supplier, the system captures complete tax information and validates it against the SAT before saving it.
Real-time RFC validation: using the SAT's web service or a validation API, the system verifies that the RFC exists, is active, and that the registered name matches what was provided.
ERP–PAC integration: the ERP or sales system builds the CFDI automatically from order data and validated recipient tax data, eliminating manual entry.
API-based cancellation management: cancellations in CFDI 4.0 require recipient acceptance in most cases. An API integration allows cancellation requests to be sent and their status queried programmatically.

How AISDC Can Help

If your business issues a significant volume of invoices or needs to integrate electronic invoicing into a proprietary system, manual processes quickly become unworkable. At AISDC, we build custom integrations between your business systems and SAT-authorized PACs — including recipient data validation, automatic CFDI issuance, and cancellation management.

Learn more about our solutions on our CFDI invoicing services page.