AT-compliant invoicing engine (pre-certification)
A working technical core for Portugal's certified invoicing rules — hash-chained RSA-SHA1 signature, ATCUD, the AT QR data string, SAF-T (PT) export and a compliant invoice layout. Fill the form to generate a live compliant preview.
Preview / pre-certification — not yet a certified fiscal invoice.
Documents generated here use a demo signing key and a placeholder certificate/ATCUD. They have no fiscal validity until the software is certified by the AT and real series codes are registered.
What full certification requires (pending)
This engine implements the technical mechanics. Becoming a legally certified fiscal invoicing solution additionally requires:
- AT software certification — a formal filing with the Autoridade Tributária; the AT assigns the certificate number that replaces the
0000/ATplaceholder. - Registered signing key — the RSA key pair whose public key is declared to the AT. Production signatures must use that key, not the runtime demo key.
- ATCUD series registration — each document series must be registered via the AT "comunicação de séries" web service, which returns the real validation code (the placeholder
0-prefix here is replaced by it). - Monthly SAF-T (PT) / e-Fatura submission — periodic reporting of issued documents to the AT.
Need compliant invoicing in Portugal today?
Our accounting team issues fully certified invoices and handles your AT obligations.