A credit note (NC) corrects a document after it has been issued, for example for a return or a discount. A debit note (ND) documents an additional charge. In SIGN PT, both are created with a CORRECTION operation that references the original document.
Always reference the original TRANSACTION record, never the INTENTION record.
Credit note or debit note in the API
The type of correction is set in each entry with entries.type. Use RETURN for a credit note, which reduces the original, and SALE for a debit note, which increases it. The direction comes from the entry type, not from the sign of the amounts.
The reason field is mandatory in Portugal. It states which elements of the original document were altered.
Rules
- A credit note uses the same VAT rates, tax region and exemption codes as the original.
- Several partial credit notes are allowed while their combined total does not exceed the original.
- SIGN PT matches each credit note line against the lines of the original, and availability is cumulative.
- A credit note cannot reference another credit note, and a debit note cannot reference another debit note.
- In CORRECTION can either have only entries of type SALE or entries of type RETURN, they are mutually exclusive. Reductions go in a credit note, and increases in a debit note or a new invoice.
- Once any credit note exists, the original can no longer be cancelled.
- When a credit note reduces the taxable base, the tax payer must keep evidence that the customer became aware of it or was reimbursed. Otherwise the VAT adjustment in favour of the supplier can be challenged (Art. 78 n.º 5 CIVA).
Credit note or cancellation?
- A cancellation is generally limited to situations where the document was issued due to an error and has had no effect for the customer: the transaction did not take place and the document was not handed over or made available.
- If the document was already issued to the customer or the supply took place, issue a credit note instead of cancelling it, for example for refunds, returns and discounts. VAT regularisation through a credit note is subject to legal deadlines.
Corrections of formal errors that do not change the taxable amount or the VAT follow separate AT rules (Ofício-Circulado 25120/2026). Confirm the procedure with a tax advisor.
What the printed credit note or debit note must show
- "Documento de origem" including the series and number of the original document. Also including the date of the original is recommended.
- "Motivo" in Portuguese.
- The items being credited. A generic text such as "Anulação da fatura" is not enough, because the credit note must refer to the elements altered (Art. 36 n.º 6 CIVA).
- Positive amounts. The direction is implied by the document type.
- Its own ATCUD, QR code and hash.
See the printed document layout guide for examples.