AT certification & compliance
Invoicing software in Portugal has to meet a demanding set of rules. This is the full map of what ARQTA implements, and of the legal basis of each part.
Self-billing - art. 36.º do CIVA (VAT Code)
In self-billing (autofaturação), the buyer issues the invoice in the name and on behalf of the supplier. The law requires a prior agreement (acordo prévio) registered by the supplier in the Portal das Finanças, authorising the buyer’s NIF. ARQTA takes care of the invitation, the step-by-step guide and the automatic check of that agreement with AT, and only issues once the authorisation exists.
Signature chain - Portaria n.º 363/2010
Each document is signed with RSA, chained to the hash of the previous document in the series, and prints 4 characters of the hash with the statement «Processado por programa certificado n.º <n.º>/AT» (processed by certified program no. <no.>/AT). The private key never leaves the server; the public key is handed to AT in the certification process (Modelo 24).
ATCUD and QR code - Portaria n.º 195/2020
Document series are reported to AT by webservice, which returns the validation code included in each invoice’s ATCUD. Every document carries the QR code with the official fields: NIFs, totals per VAT rate, withholding, hash and certificate number.
SAF-T (PT) - Portaria n.º 302/2016
SAF-T export in version 1.04_01, validated against the official XSD: one file per supplier, with cancelled documents included (status «A»), credit notes with References, taxes by tax region and withholding tax. Ready to hand to AT or to the accountant.
e-Fatura - document reporting
Every invoice and credit note is reported to e-Fatura through AT’s official webservice, with WS-Security authentication by sub-user and the full tax details (VAT per rate, exemptions with a reason code, withholding tax).
Certification status
ARQTA is going through certification with AT (application submitted with the Modelo 24 declaration; compliance tests under way). This page will be updated with the certificate number once it is assigned. Until then, test documents use the provisional number that AT itself sets for the process.