Mexico: CFDI

Mexico is outside the EU; CFDI 4.0 (and 3.3 in older files) is supported because it is a clearance format with the same withholding and extra-tax concerns. cfdi:Comprobante with TipoDeComprobante I is an invoice and E (egreso) a credit note. T (traslado), P (pago, Pagos 1.0/2.0) and N (nómina) are not invoices: detection returns them as other documents with their own label, and convert reports not-an-invoice.

CFDI	Canonical
Emisor / Receptor Rfc	nationalTaxIds with scheme MX:RFC (no vatId: Mexican IVA has no VAT number). NumRegIdTrib of a foreign receiver is a second national id
RegimenFiscal, RegimenFiscalReceptor, DomicilioFiscalReceptor, UsoCFDI, ResidenciaFiscal, LugarExpedicion, Exportacion, MetodoPago, FormaPago, InformacionGlobal, issuer Sello / NoCertificado	extensions.mx. The receiver’s postal code is also buyer.address.postalCode; the issuer has no address in a CFDI
Concepto	lines: ClaveProdServ is an item classification (MX:ClaveProdServ), ClaveUnidad is unitCode (SAT’s catalogue is UN/ECE Rec 20 plus a few SAT codes) and Unidad is unitText; ObjetoImp and ClaveUnidad are kept in line.national. Descuento is a line allowance and netAmount is Importe - Descuento
Traslado IVA (002)	vatBreakdown and line.vat: Tasa 0.16 is S with rate 16, Tasa 0 is Z, Exento is E. ObjetoImp 01 gives O
Traslado IEPS (003) and others	otherTaxes (MX:IEPS, includedInTotal)
Retenciones ISR (001), IVA (002), IEPS (003)	withholdings (MX:ISR, MX:IVA), totals.withholdingTotal; the line-level base and rate are on line.withholdings
SubTotal, Descuento, Total	lineNetTotal = taxExclusive = SubTotal - Descuento, payable = Total, taxInclusive = Total + retenciones. The original SubTotal and Descuento are in extensions.mx
FormaPago	payments[]: 01 cash (10), 02 cheque (20), 03 transfer (30), 04 credit card (54), 28 debit card (55); the rest are ZZZ with the SAT label
CfdiRelacionados	precedingInvoices: the UUID is id and clearanceId, TipoRelacion is relationType (01 credit note, 04 substitution…)
TimbreFiscalDigital	clearance with authority MX:SAT: UUID, FechaTimbrado, NoCertificadoSAT, SelloSAT (not verified), and the PAC (RfcProvCertif) as intermediary

What the model cannot say, and where it goes:

• No generic tax model. Every CFDI tax fits vatBreakdown, otherTaxes or withholdings, but two things are lost in shape. IEPS as a fixed amount per unit (TipoFactor Cuota) has no rate: otherTaxes[].rate is left out and MX-TAX-CUOTA is warned (the amount and the quantity base are kept). Document-level retenciones state no base or rate in a CFDI, so withholdings[].taxableAmount and rate are empty there; the lines carry them.
• Local taxes (complement Impuestos Locales, for example the lodging tax) change Total but are not mapped, so the BR-CO-15 / 16 totals check will warn on such files; MX-COMPLEMENT-UNMAPPED names the complement. The same warning covers Comercio Exterior, Carta Porte, INE and every other complement except the stamp.
• IVA Exento has no Importe; the breakdown uses a tax amount of 0. CFDI 3.3 states no Base at document level, so it is summed from the lines (recorded in source.derived).
• Fecha has no time zone; the time goes to issueTime as written. Amounts are in Moneda; TipoCambio (conversion to MXN) is exchangeRate.
• The issuer’s Sello is a digital seal over the original string, not an XML signature, and is not verified. The same holds for SelloSAT.
• Addenda, Parte, ACuentaTerceros and ComplementoConcepto are not mapped.

Run scripts/sweep.ts over a few months of your real inbound files before building phase 2. It shows which formats you actually receive.