- In Portugal the program itself has to be certified by the AT, not just the document.
- Series are communicated to the AT, and that's where the identifier that goes into the ATCUD comes from.
- Every document carries an ATCUD and a QR Code.
- The SAF-T (PT) is the standardized file submitted to the AT.
- Promec is not certified software in Portugal. Invoicing stays in your current program.
Anyone coming from another country and arriving in Portugal finds a fundamental difference: here the law doesn't just define what the invoice has to look like. It defines what the program has to look like. That's why you can't simply install any foreign software and start invoicing.
Certification: what changes in practice
A certified program has a number assigned by the AT that appears on the documents it issues. To get there it has to guarantee, among other things, that documents can't be altered once issued and that each one is signed, chaining to the previous one. It's the same principle that appears in other countries as a "hash chain," but here it's verified in the program itself, not just in the document.
You can't keep two programs issuing under the same series. If the shop starts writing receipts outside the certified program, the sequence breaks — and that shows up in the SAF-T.
Communicated series and ATCUD
Before issuing under a new series, it's communicated to the AT and an identifier is received. That identifier, together with the document's sequential number, forms the ATCUD, printed on the document along with the QR Code. The QR lets whoever receives the invoice look it up without having to copy it by hand.
SAF-T (PT)
It's a file with invoicing information in a standardized format. It comes out of the program and is submitted to the AT. From the point of view of someone choosing software, the SAF-T is a good test: a program that generates it correctly is a program that has its information organized internally.
What the shop can organize already
Even with invoicing in a separate program — which is Promec's situation in Portugal —, there's work that decides whether invoicing is fast or a second job:
- Quotes with labor and parts in separate lines, from the start.
- Complete customer tax details on file, including the NIF.
- A work order closed with the final amount, with no sums done by hand.
- Clean export to the invoicing program and to the accountant.
A shop organized this way can switch invoicing programs without drama. One that works on paper is going to struggle with any of them.
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