Technical articles on e-invoicing, API integration, and Mexico's tax ecosystem.
How to validate the XML of a received CFDI against the Anexo 20 XSD: schemaLocation, declared complements, and the errors that break parsing.
What the SAT's Lista 69-B is, what each stage means, the 30-business-day window after a definitive listing, and how to screen suppliers automatically.
Replace a CFDI with errors step by step: issue the new CFDI with relationship type 04, then cancel the original with reason 01. What the SAT checks.
A PAC (Proveedor Autorizado de Certificación) stamps CFDIs so they're valid for tax purposes. What it does, how it relates to the SAT, and how to choose one.
Send your own folio number with each invoice in Fiscalapi or let it assign one automatically, now without the gaps that rejected invoices used to leave.
Carta Porte explained: the CFDI complement that documents goods moved in Mexico, version 3.1 requirements, who must issue it, and cross-border shipping.
The DIOT is Mexico's monthly informative return on supplier transactions and their VAT: who files it, the deadline, and how to build it from CFDIs.
Mexico e-invoicing requirements for foreign companies: the CFDI, the PAC, CSD and e.firma certificates, the issuance flow, and your integration options.
Running payroll in Mexico as a foreign employer: ISR withholding, IMSS and INFONAVIT, the state payroll tax, mandatory benefits, and the payroll CFDI.
Mexico VAT (IVA) for foreign companies: the 16% rate, the 8% border zone, zero-rated exports, VAT on digital services, withholding, and the CFDI.
What Mexico's RFC tax ID number is, its format with examples for individuals and legal entities, generic RFCs for foreigners, and how to validate one.
The folio fiscal is the UUID a PAC assigns when it stamps a CFDI. What it means in English, where to find it on an invoice, and how to verify it.
What a CFDI addenda is, how it differs from a SAT complement, why Mexican retailers require one, and how to add it to an invoice without delaying payment.
Every c_TipoRelacion code from 01 to 07, when to use each one, the 04 substitution that most people get wrong, and the errors that block a cancellation.
How to find the right ClaveProdServ for each CFDI line item: what the 8 digits mean, a decision tree, the most used keys, and the mistakes the SAT flags.
SAT unit of measure codes (c_ClaveUnidad) for CFDI: how ClaveUnidad relates to ClaveProdServ, the 30 most used keys, and how to pick one for services.
How the Comercio Exterior complement works on income and transfer CFDIs for exports, which fields the SAT checks, and the errors that get exports rejected.
What the Carta Manifiesto is, why your PAC asks for it, who must sign it with an e.firma, and how to send it to your customers from Fiscalapi.
Cancel a CFDI 4.0: the four cancellation reasons, when the recipient must accept, the statuses, deadlines, the API flow, and the most common errors.
When to issue a credit note (Egreso CFDI) in Mexico, its structure and relationship types, the tax treatment, and how it differs from canceling an invoice.
How to issue a CFDI 4.0 global invoice for sales to the general public: generic RFC XAXX010101000, the InformacionGlobal node, periodicity, and deadlines.
When to use Mexico's generic RFCs on a CFDI: XAXX010101000 for the general public and XEXX010101000 for foreign customers, and the fields each one needs.
The official 2026 ISR tables from Anexo 8 of the RMF: monthly, semi-monthly, and annual brackets, with a step-by-step withholding example for payroll.
The payroll CFDI explained: the Nómina 1.2 complement structure, earnings, deductions, OtrosPagos, ISR withholding, deadlines, and common stamping errors.
Check that a CFDI is authentic and still valid: the SAT portal, the web service, and an API. What each status means, cancelability, and the QR shortcut.
CFDI 4.0 for developers: XML structure, required issuer, recipient, and item fields, what changed from 3.3, the CFDI types, and how to issue one by API.
When an advance payment needs its own CFDI, the flow from advance to final invoice with relationship type 07, common mistakes, and how to automate it.
CFDI form of payment: every SAT code (forma de pago), when to use each, how it differs from the payment method, and the mistakes to avoid.
When a PPD invoice needs a payment complement, the flow from invoice to payment CFDI, what changed in version 2.0, and the errors that get it rejected.
How CFDI stamping works: what the PAC validates, what the digital tax stamp adds, the most common stamping errors, and how to automate it with an API.
How the SAT bulk download web service works: e.firma authentication, download requests, status polling, and packages, and why it is hard to use directly.
CFDI meaning: Mexico's electronic invoice explained. How a CFDI is issued and stamped, the CFDI types, and how to issue one from your system with an API.