Nota de Crédito
Credit Note
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A certified fiscal document that corrects or partially reverses a previously issued invoice. Required in Portugal because invoices cannot be edited or deleted once issued.
In Portugal, once you issue an invoice, it's permanent. No edits, no deletions, and the tax authority (AT) gets a record of it, in real time if your software reports over the webservice and by the 5th of the following month otherwise.
There are two ways to put that right, and they are not interchangeable. A Nota de Crédito is the one for when the money changes: you overcharged, the client returned the goods, the contract was cancelled after you billed it. When the money doesn't change, or the sale never happened at all, you cancel the invoice instead.
How it works
A Nota de Crédito (NC) is a certified fiscal document that references an original invoice and reverses all or part of it. It must include:
- The number of the original invoice it corrects
- The amount being corrected (partial or full)
- The reason for the correction
The NC is issued through the same certified invoicing software you use for your faturas. It gets its own sequential number in the NC series and is signed and reported to the AT, just like any other document in the chain.
The effect depends on the original document
What happens after you issue an NC depends on the type of invoice it corrects:
- FT (fatura): The original invoice created a payment obligation. The NC reduces or eliminates that obligation. If the client hasn't paid yet, they now owe less (or nothing).
- A document that was already paid: an NC against it creates a refund obligation, you owe the client money back. That turns on whether the invoice was actually settled, not on which type it is. A fatura-recibo usually is paid on issue, and a fatura simplificada is a reduced-content invoice that may well be outstanding.
An NC can also reduce the VAT you report for the period, but that part is not automatic. Taking VAT back in your own favour is optional, and if you do take it, Art. 78.º n.º 5 CIVA requires you to hold proof the client knew about the correction or was reimbursed. Silence does not count: AT rejected deemed acceptance after a waiting period outright. If the credit note mentions no VAT at all, you have elected not to regularise and there is nothing to report.
When it's a credit note, and when it's a cancellation
Two questions, in order. Did the sale happen at all? If it did, does the correction move the taxable amount or the VAT?
What does not decide it is whether you already sent the invoice, or whether the client has seen it. That is the rule most people assume and the one AT's current guidance contradicts. Note the narrow scope of that: the client's knowledge does not pick the instrument, but it does decide whether you may take the VAT back, which is a separate question and is covered above.
- Neither the amount nor the VAT moves. A wrong NIF, a wrong address, a description that doesn't match what you delivered. Cancel the invoice (anular) and issue a corrected one. No credit note, and no VAT correction is owed.
- The sale never happened. You invoiced something that didn't take place. Cancel it. There was no transaction, so there is nothing to credit. A job billed twice most likely belongs here too, for the reason below.
- The sale happened, then it was undone or reduced. A return, a cancelled contract, a discount agreed afterwards. This is the credit note, under art. 78.º n.º 2 CIVA.
A correction that moves the VAT and leaves the amount alone is its own case, and how it is handled changes at the end of 2026. If that is yours, ask before you reach for either instrument.
The last two look identical in Portuguese and are not. Inexistência de operação means it never happened. Anulação da operação means it happened and was later unwound. They take opposite instruments, and the words are close enough that people reach for the wrong one.
A credit note cannot be used to void an invoice. AT states this directly: its use must be limited to correcting the elements that actually need correcting, so that it isn't used as an instrument for cancelling invoices.
Correction reason is mandatory
A blank NC is not something you can issue. A correction has to say what it is correcting, whether that's a pricing error, a service cancellation, or a return, and the reason travels with the certified document to the tax authority.
A duplicate invoice is not on that list, and it's the one people get wrong. Billing the same job twice leaves the second document with no supply of its own behind it, which puts it on the cancellation side rather than the credit-note side.
That last one is a reading rather than a rule. AT has not addressed duplicates directly, and its own invoicing app offers a cancellation reason that belongs to the credit-note path, so you can meet the opposite advice from AT itself. Worth confirming with your accountant if anyone disputes it.
This isn't bureaucracy for its own sake. The document chain tells a complete story: invoice issued, correction made, reason recorded. Every NC is traceable back to the original invoice it corrects.
Perguntas frequentes
O que é uma Nota de Crédito?
A Nota de Crédito (NC) is a fiscal document that corrects a previously issued invoice. Since invoices in Portugal can never be deleted or modified after issuance, the NC is how you reverse an overcharge or account for a returned product. It is one of two routes: when the amount and the VAT are both right and something else is wrong, you cancel the invoice and issue a corrected one instead.
When do I need to issue a Nota de Crédito?
When the amount on an invoice you already issued turns out to be wrong in the client's favour, or the sale was undone afterwards: you charged too much, the client returned goods, the contract was cancelled. The NC references the original invoice and states the reason.
Should I issue a Nota de Crédito or cancel the invoice?
The test is whether the taxable amount or the VAT changes. If neither moves, a wrong NIF, a wrong address, a description that doesn't match, you cancel the invoice (anular) and issue a corrected one. If the sale never happened, you cancel it too, and a job billed twice most likely belongs there, though AT has not addressed duplicates directly. The credit note is for a real sale that was later undone or reduced, which is art. 78.º n.º 2 CIVA. A credit note may not be used to void an invoice.
Can I just delete an invoice instead of issuing a Nota de Crédito?
No. Portuguese law requires all certified documents to be permanent. Once an invoice is issued, it exists in the system forever, sequentially numbered and reported to the tax authority. You correct it either with an NC that references it, or by cancelling it and issuing a corrected one, depending on what is actually wrong. Neither removes the original.
Does a Nota de Crédito affect my VAT?
It can, but not automatically. Regularising VAT in your own favour is optional, and Art. 78.º n.º 5 CIVA conditions it on holding proof the client knew about the correction or was reimbursed. If you charged 23% VAT on an invoice and then issue a full NC, the VAT on that invoice is reversed, provided you are entitled to regularise it. The tax authority holds both documents; you declare the net position.
How is a Nota de Crédito numbered?
Like all certified documents in Portugal, an NC gets a sequential number within its own series (NC series). It's part of the same signed document chain as your invoices, issued through certified software and reported to the AT.