Argentine businesses are legally required to issue AFIP-authorized electronic invoices, where every Factura must carry a valid CAE (Código de Autorización Electrónico) obtained from AFIP's WSFEv1 web service before it can be delivered to a customer. ERPNext core gives you a solid Sales Invoice, tax templates, and a customer master, but it has no concept of a CAE, no WSAA token/sign handshake to authenticate against AFIP, no notion of Punto de Venta, comprobante types 001/006/011 (Factura A/B/C), or the CbteTipo/Concepto codes AFIP expects. Teams end up copy-pasting totals into AFIP's web portal or a third-party tool, then reconciling by hand — which is slow, error-prone, and breaks the moment invoice volume grows.

We build a proper Frappe app (for example erpnext_afip) with its own module, so nothing is hacked into ERPNext core and the whole thing survives bench update. The app adds custom DocTypes such as AFIP Settings (credentials, CUIT, environment homologación vs. producción, certificate/private-key references), AFIP Punto de Venta, and an AFIP CAE Log that stores every request/response, the returned CAE, its expiry, and any AFIP observation codes for audit. A hooks.py doc_events handler on Sales Invoice on_submit calls a whitelisted server-side method that performs the WSAA login (signed CMS ticket → token + sign, cached until expiry via a Frappe cache/scheduler), maps the invoice to the correct CbteTipo and Concepto, resolves the buyer's DocTipo/DocNro from a validated CUIT, builds the IVA array from your ERPNext tax rows (21%, 10.5%, 27%, exempt), applies perception/retention (percepciones/retenciones) as separate tributo lines, and submits FECAESolicitar. On success the returned CAE, CAE vencimiento, and comprobante number are written back to custom fields on the Sales Invoice; on rejection the AFIP error is surfaced cleanly and submission is blocked so you never ship an unauthorized invoice.

Around that core we wire the details that make it usable day to day: CUIT validation with the check-digit algorithm at the point of entry (client script) and server-side re-validation, automatic next-number sequencing per Punto de Venta reconciled against FECompUltimoAutorizado, electronic credit note (Nota de Crédito, types 003/008/013) support with reference to the original comprobante, and a print format that renders the legal PDF with the AFIP QR code and CAE/vencimiento block. Because everything is exposed through the Frappe REST API and whitelisted methods, you can also trigger authorization from custom flows, and role profiles/permissions keep CAE requests limited to your accounting roles. The app targets Frappe/ERPNext v15 and v16.

This is a build-to-order engagement, not a one-click marketplace download. After a short scoping call we confirm your exact requirements — which comprobante types you issue, your Puntos de Venta, IVA/perception configuration, and whether you need multi-company — and hand you a fixed scope. We build against your version on a staging bench, run UAT with your team using AFIP's homologación environment, then install into production, hand over the git repository, and stay with you through a post-go-live support window. Typical delivery is one working week from confirmed scope.