Glossary · heru API

SAT: Servicio de Administración Tributaria, Mexico's federal tax authority. It keeps the taxpayer registry, issues digital certificates and receives every electronic invoice.
IMSS: Instituto Mexicano del Seguro Social, the institution that runs social security for workers in Mexico.
RENAPO: Registro Nacional de Población, the population registry that issues and validates CURPs.
CURP: Clave Única de Registro de Población. An 18-character personal identifier issued by RENAPO to every person living in Mexico. It is the most reliable starting point for a fiscal validation, because a person has exactly one.
RFC: Registro Federal de Contribuyentes, the taxpayer id issued by the SAT: 13 characters for individuals, 12 for companies. A person can have a CURP and no RFC, or an RFC that is suspended. XAXX010101000 is the generic RFC for the general public.
Régimen fiscal (tax regime): The tax regime a taxpayer is registered under, identified by a code from the SAT catalog c_RegimenFiscal. Examples in these docs: 625 for income through technology platforms, 626 for the Régimen Simplificado de Confianza (RESICO), 612 for business and professional activities, and 601 for companies under the general regime. A person can have more than one.
e.firma: The advanced electronic signature issued by the SAT (formerly FIEL): a certificate and a private key protected by a password. It identifies the taxpayer before the SAT and is required to obtain a CSD.
CSD: Certificado de Sello Digital. A certificate the SAT issues to a taxpayer, obtained with their e.firma, used only to seal their invoices. Someone who issues invoices in their own name needs an active CSD.
CFDI 4.0: Comprobante Fiscal Digital por Internet, Mexico's electronic invoice, now in version 4.0. An XML document sealed with the issuer's CSD and stamped by a PAC. Version 4.0 requires the receiver's name, postal code and tax regime to match the SAT's records exactly, which is why heru validates them first.
PAC: Proveedor Autorizado de Certificación. A company authorized by the SAT to validate and stamp CFDI. heru stamps through PACs.
UUID (folio fiscal): The unique id the stamp assigns to every CFDI. It identifies the invoice before the SAT, for example to cancel it.
CFDI de retenciones (retention certificate): The electronic document that records the ISR and VAT a company withheld from someone's payments. The company that withheld issues it. Some platforms call it CRIP (constancia de retenciones e información de pagos).
Complemento de servicios de plataformas tecnológicas: The part of a CFDI de retenciones (retention code 26) that lists the services sold through a digital platform: dates, prices, VAT, commissions and totals. heru builds it from platform.services.
c_CveRetenc: The SAT catalog of reasons for a withholding. 26 is services through digital platforms; 25 is other, with a description.
c_TipoPagoRet: The SAT catalog that says how a withholding counts for the receiver: 01 definitive VAT, 02 definitive IEPS, 03 definitive ISR, 04 provisional ISR.
c_TipoDeServ: The SAT catalog of services sold through platforms, from 01 passenger transport to 09 distance learning. It sets the ISR rate; see the retention certificates guide.
c_Periodicidad: The SAT catalog of how often something is paid or reported: 01 daily, 02 weekly, 03 biweekly, 04 monthly, 05 bimonthly. Global invoices and the platforms complement use it.
Customer: A persona física one of your companies sells to (13-character RFC). Send receiver.customer_id (cus_…) on an invoice or a retention certificate and heru takes the RFC, name, regime and postal code it already has. A business that sells through your terminal is a merchant, and a person you pay is a worker.
ISR and IVA: Impuesto Sobre la Renta (income tax) and Impuesto al Valor Agregado (value added tax, VAT). Platforms withhold part of both from the payments they make to independent workers.
Por cuenta de terceros: An invoice issued by one party on behalf of another. When an invoice carries the worker in third_party, heru issues the CFDI on the worker's behalf, so the worker does not need their own CSD.
Factura global (global invoice): A single invoice to the general public, issued periodically, that covers the sales nobody invoiced individually.
NSS: Número de Seguridad Social, the 11-digit number the IMSS assigns to a person. A person without one can be registered.
c_FormaPago: The SAT catalog of payment forms. The ones used here: 03 bank transfer, 04 credit card, 28 debit card.
c_UsoCFDI: The SAT catalog of what the receiver will use the invoice for. G03 means general expenses.