How to issue self-billed invoices and generate their SAF-T

What is it for?

In self-billing, your company issues the invoice for a purchase, on behalf of the supplier, because you have an agreement to do so. In fiscaldoo, that invoice comes from a dedicated purchase journal and goes into a separate SAF-T file (mode S), with one file per supplier.

What makes a document self-billed is the journal it comes from, not the agreement. A normal sale to a customer who also has an agreement is still a normal sale, and an invoice from this journal goes into the mode S file even if the agreement is not registered on the contact. The program does not refuse an invoice because the agreement is missing: make sure it exists before you issue the invoice.

When to use it?

• When you buy from a supplier with whom you have a self-billing agreement and your company issues the invoice.
• When you need the SAF-T file of those invoices, for one supplier or for all suppliers with an agreement.
• It is not for recording the invoice the supplier sent you: that is a normal supplier invoice.

Where to find it?

• Agreement: Accounting › Record › Suppliers › open the supplier › Billing tab.
• Journal: Accounting › Configure › Create a journal.
• Series: Accounting › Configure › Fiscal series.
• Invoice: Accounting › Record › Supplier invoices.
• File for one supplier: Accounting › Declare › Generate SAF-T.
• Files for several suppliers: Accounting › Declare › What is there to do with the SAF-T?, under Supporting lists, Self-billing.

Before you start

• The Fiscal officer profile, which can do every step in this article. The Accountant can generate the file, but cannot change the journal's PT Certification tab.
• The written agreement with the supplier, with its date and reference. Pending validation by a certified accountant: the conditions of the VAT Code (CIVA), art. 36.º n.º 11 (written agreement, proof that the supplier accepted the content of the invoice, and the words “autofaturação” (self-billing) on the document).
• The products you will invoice, each with an internal reference. The program refuses to confirm an invoice with a line that has no product (see “Common problems”).

How to use it

The screenshots come from the demo database, where the AT is replaced by a simulator.

Register the agreement on the supplier's form

1. Open the supplier and the Billing tab.
2. In the Self-billing (CIVA art. 36.º n.º 11) block, switch on Self-billing agreement. The Self-billing agreement date becomes required.
3. Fill in the date and the Self-billing agreement reference, and save.

Create the self-billing purchase journal

Only once. The demo does not include one.

1. In Create a journal, choose Purchases (supplier invoices) and click Next.
2. Fill in Journal name and Short code (in the example, “Autofaturação de compras” and “AUTOF”), click Next and then Create journal.
3. In the journal, open Advanced Settings and switch on Self-billing.
4. Open PT Certification, switch on Journal certified, and choose [FT] Invoice in SAF-T document type and [NC] Credit note in SAF-T document type (credit notes).
5. Save. Secure Posted Entries with Hash is switched on automatically.

Create the journal's series

You need one series for invoices and another for credit notes, each communicated to the AT. The steps are in How to create a series and communicate it to the AT: in Journal, choose the journal you created. In the example, the invoice series is AF26.

Issue the invoice

1. In Supplier invoices, click New and choose the Supplier.
2. In Journal, choose the self-billing journal. Check that the right journal is selected: by default, the invoice goes to the normal purchase journal.
3. In Bill Date, enter a date on or after the start of the series.
4. In Add a line, choose the Product and fill in the Quantity and Price. Check the Taxes.
5. Click Confirm. The document receives its number, ATCUD and signature, and can no longer be changed.

Invoice FT AF26/4, for €250.00 plus 23% VAT, produced these lines in the ledger:

Account	Debit	Credit
311 Mercadorias (Goods)	€250.00
2432 IVA - Dedutível (Deductible VAT)	€57.50
2211 Fornecedores gerais (General suppliers)		€307.50

Generate the file for one supplier

1. In Generate SAF-T, choose S — Self-billing in Mode.
2. In Self-billing partner, choose the supplier. The list shows all contacts, not only those with an agreement: make sure you choose the right supplier.
3. In Reference date, choose a day in the month you want.
4. Check the number on the button, which counts that supplier's documents in the period (in the example, Generate with 1 documents), and click it.
5. In the export, check the Generated status and click Download file. The name looks like SAFT-PT_509999999_2026_11_S.xml.

Generate the files for several suppliers

1. In What is there to do with the SAF-T?, open Self-billing and click New.
2. Fill in Date From and Date To. In Partners, choose some, or leave it empty for all partners with an agreement or with documents in the period. Save.
3. Click Generate files and check the counters: Files in the ZIP, Invalid files (not in the ZIP) and Partners without documents.
4. In the list, the supplier marked Invalid is left out of the ZIP, with the reason: click Open the export to see what to fix. The others show the file name in File in the ZIP.
5. Click Download the ZIP.

The Register the sending button asks for confirmation: “No message goes out from a test database. In a production database the message is placed in the mail queue of this database.” In the demo, the line stays Not sent, with “Not sent: test environment.”. Pending on-screen validation: what reaches the supplier in a production database cannot be seen in the demo.

Expected result

We opened the two November files. The self-billed invoice and a normal sale to the same partner, who has an agreement, came out like this:

Document	File	Type	Document status	Self-billing indicator
FT AF26/4 (self-billing journal)	Mode S	FT	S	1
FT D26/35 (normal sale)	Mode F	FT	N	0

• The agreement still counts on the partner's form: in both files, the customer list shows the partner with indicator 1. A supplier without an agreement appears in that list with indicator 0, and the document still has indicator 1.
• In the mode S file, the supplier appears in the customer list (Customer) and only what came from the self-billing journal is included.
• The self-billed invoice is not included in the mode F billing file.

Important notes

• Sending to the AT. The self-billed invoice has no Communicate to the AT button. A normal sale to a partner with an agreement is communicated like any other. In the example, FT D26/35 became Accepted (simulated) in Communications with the Tax Authority, and the Request carries "self_billing": false: it is not flagged as self-billing. The demo uses the AT simulator; nothing reached the real AT.
• Submitting the file. Pending validation by a certified accountant: whether the mode S file is submitted to the AT, to whom and by when.
• Old files. If you generate a past period again, the new file follows today's rule. The old file is kept and no document changes.
• PDF. The PDF has the title “Invoice - Self-billing FT AF26/4”.
• Removing the agreement. Invoices already issued in this journal still go into that supplier's mode S file. Talk to your certified accountant before removing an agreement.

Common problems

• Symptom: when you click Confirm, “The invoice cannot be posted yet: some lines do not meet the rules of the Tax Authority. - Line 1 (Free line): choose a product or service with “Internal Reference”. The Tax Authority requires a product code on every invoice line. […] Correct the lines above and confirm again. Nothing was posted and no number was used.” Solution: on each line, choose a product with an internal reference and a unit of measure, and confirm again.
• Symptom: when you generate the file, the status becomes Invalid, with the message “Line 1 of entry "FT AF26/1" has no product: choose an article in the “Product” column of that line (a line with free text cannot be reported to the Tax Authority).” Solution: this happens with an invoice issued before the program refused these lines, and a confirmed document can no longer be changed. Talk to your certified accountant. If they advise it, cancel it with Cancel certified document: generated again, the file comes out Generated, with the invoice cancelled and the generic product SERV.
• Symptom: the file stays Invalid, with “There are no self-billed documents of "…" in this period, so no self-billing file was made. […] How to fix it: Check the supplier and the dates. Only documents confirmed in the self-billing journal count; removing the agreement does not make invoices already issued disappear.” Solution: check the supplier, the dates and the journal of each invoice, and generate again.
• Symptom: in Self-billing, “These partners have no self-billing agreement and no self-billed documents in the period, so no SAF-T (PT) of mode S can be made for them: Sapataria. Register the agreement on the partner (CIVA art. 36.º n.º 11) or remove them from the selection.” Solution: do what the message says.
• Symptom: when you confirm the invoice, “The document "(no number yet)" is dated 31/10/2026, before the planned start date of series "FT AF26" (04/11/2026).” Solution: enter a date on or after the start of the series, or ask the fiscal officer to communicate a series that covers that date.
• Symptom: when you confirm a credit note, “Journal "Autofaturação de compras" does not have a single active fiscal series of type [NC] Credit note for fiscal year 2026”. Solution: create and communicate this journal's credit note series, in Configure › Fiscal series.
• Symptom: “Some required fields are empty. Fill in the fields marked in red to be able to save.” Solution: on the form, the Self-billing agreement date is missing. In Generate SAF-T, the Self-billing partner is missing.

Other file errors: How to fix SAF-T errors.