What is a credit note? Rules, VAT and when to issue one

You sent the invoice on Monday. On Wednesday the customer emails to say the quantity is wrong, they were billed for three licenses instead of two, and could you just fix it and resend. You open the invoice and find you cannot change a thing.

That is by design, and the document that fixes it is a credit note.

This post covers what a credit note is, when to issue one, and what has to go on it. Then it covers the parts most explanations skip: how it differs from a refund, why the original invoice is locked, and what the whole thing does to your VAT return.

What is a credit note?

A credit note is the instrument for correcting an invoice after it has already gone out, either cancelling it or knocking down its value. It does not replace the original. The two documents sit side by side and are read together to give the net position.

That design is the point. HMRC puts it plainly: credit notes "amend or correct previously issued invoices; the invoices are the documents that evidence taxable supplies". The invoice stays as evidence of what happened. The credit note records what changed.

A credit note can be full, cancelling an invoice outright, or partial, reducing it by a line or an amount. In our three-licenses example, you would credit one license and leave the rest of the invoice standing.

One point of confusion worth clearing early: credit note, credit memo, credit memorandum and credit invoice are all the same document. "Credit memo" is the usual term in US accounting and accounts payable software. "Credit note" dominates in the UK and EU. If you want the wider tour, we cover the most common types of invoices separately.

When do you issue a credit note?

The trigger is usually simpler than the paperwork suggests. You issue one when the amount on an invoice you already sent is no longer the amount owed.

The common cases:

• An error in the initial invoice: wrong quantity, wrong price, wrong tax rate, or the wrong customer details
• Goods returned, or a service cancelled after you invoiced for it
• A discount, rebate or goodwill gesture agreed after the invoice went out
• A partial refund where the customer keeps part of the order
• An invoice sent to the wrong customer altogether
• Writing off an invoice you have accepted will never be paid

That last one is worth pausing on, because most explanations skip it. A credit note can cancel an invoice the customer never paid. No money moves in either direction. You are correcting a receivable that was never going to arrive, not returning anything.

Which points at what a credit note is not. It adjusts what is owed. By itself, it moves nothing.

Why you cannot just edit or delete the invoice

This is the question most people actually arrive with, and the answer is more interesting than "the software won't let you".

An issued invoice is a legal record of a taxable supply. It is not a draft, and it stopped being yours to revise the moment it went out. Three things follow from that.

1. Invoice numbering has to stay sequential and unbroken. Delete an invoice and you leave a gap in the sequence. A gap is precisely what an auditor looks for, because it is what invoice fraud looks like. The credit note carries its own number in its own series, so both sequences stay intact.
2. The audit trail has to show the correction, not hide it. A "fixed" invoice that quietly replaces its predecessor destroys the evidence that anything changed. The credit note leaves that document standing, records the change, and shows the net result.
3. Under e-invoicing mandates the invoice has usually already gone. Where structured e-invoicing is in force, the document was transmitted to a tax authority at the moment of issue. It cannot be recalled, edited or unsent, even in principle.

If you are unclear on what makes an invoice a legal document rather than a request for payment, our guide to what a tax invoice is covers the requirements.

Credit note vs refund vs debit note

Three documents, routinely confused, doing genuinely different jobs. The short version: a credit note adjusts what is owed, a refund moves money, and a debit note adjusts the amount upward rather than down.

Document	Who issues it	Direction	Does money move?
Credit note	Seller	Reduces the amount owed	Not by itself
Refund	Seller	Returns money already paid	Yes
Debit note	Often the buyer	Increases the amount owed	Not by itself

A credit note often comes before a refund, but it does not require one. The customer might take the credit against their next order instead, which is what happens with most subscription adjustments. Back at the three-licenses invoice: if the customer has not paid, the credit note reduces what they owe and that is the end of it. If they have paid, the credit note records the correction and the refund returns the money. Our guide to refunds for digital businesses covers the money-moving side.

What to include on a credit note

In the UK, HMRC is direct about this: a credit note "must contain the same details as a VAT invoice". In practice that means:

• The words "credit note", clearly, so it cannot be mistaken for an invoice
• Its own sequential number, from a series separate to your invoices
• The date of issue
• A reference to the original invoice number and its date
• Seller and customer details, including VAT numbers wherever the initial invoice carried them
• A line-by-line description of what is being credited
• Net amount, tax rate, tax amount and gross amount, mirroring how the invoice presented them

Two of those get glossed everywhere and matter more than the rest:

Stating the reason for the credit is not universally mandated, but include it anyway. It is the first thing anyone reviewing the document will ask.

On timing, HMRC expects you to issue the credit note "within a reasonable time of the event giving rise to the adjustment", and to agree the adjustment with your customer wherever possible.

What a credit note does to your VAT

This is where most explanations stop, and it starts with a principle that surprises people.

HMRC states it directly: "The VAT liability is determined by the underlying supply position, not by the issue or receipt of a credit note".

Read that twice if you are tempted to solve a problem by crediting it away. If the supply happened and VAT was due, VAT was due. A credit note documents a genuine change to the consideration and the VAT follows that change. It is evidence, not a lever.

The UK statutory basis sits in Regulations 15, 15C, 24A and 38 of the VAT Regulations 1995, which is where HMRC's manual points.

Which return period the adjustment lands in

This one is good news. You do not reopen a filed return.

HMRC's guidance is that you "must account for the adjustment on the VAT Return for the period in which you issue the credit note". So a credit note raised in Q3 against a Q2 invoice reduces your Q3 output VAT. The Q2 return you already filed stays as it was.

That makes the issue date a number that matters, not an administrative detail. Our walkthrough on preparing a VAT return shows where the adjustment lands, and input VAT versus output VAT explains the figure it reduces.

Cross-border credits

This is where the real difficulty sits.

• Reverse-charge supplies. The initial invoice carried no VAT because the customer accounted for it. The credit note carries none either. Both parties still adjust their records, and both still report the change. Our explainer on how the reverse charge mechanism works covers the underlying logic.
• Sales reported through OSS or IOSS. You do not amend the return you already submitted. For returns from July 2021 onward, corrections go into a subsequent OSS return, and the European Commission confirms member states allow corrections "within three years of the date on which the initial return had to be submitted". Corrections and new supplies for the same country are offset against each other to reach the balance. If you sell across the EU under OSS or IOSS, this is the mechanism to know.

Credit notes under e-invoicing mandates

Where structured e-invoicing is mandatory, the credit note is mandatory in the same structured format. It is not a PDF attached to an email, and it is not a layout you design.

The format also enforces what was best practice a moment ago. A structured credit note carries a machine-readable reference to the document it corrects, so that link stops being a courtesy to your accountant and becomes a validation rule. Get it wrong and the file is rejected before it ever reaches a tax authority.

Several EU countries already have mandates live or scheduled, each with its own format and transmission route. The detail differs enough that it belongs in its own guide: we cover what e-invoicing is and how it works, and the practices that keep you compliant across jurisdictions.

Credit notes for subscriptions and digital products

Most credit note advice assumes a returned physical good. If you sell software or digital products, yours look nothing like that.

• Mid-cycle downgrades. A customer dropping from ten seats to six halfway through a quarter generates a prorated credit. At any scale that is a monthly volume problem, not a one-off.
• Cancellations part-way through a paid period. Whether you credit the unused portion depends on your terms. If you do, it is a credit note.
• Chargebacks are not credit notes. A chargeback is a payment event forced by the card network. It may lead you to issue a credit note, but it is not one.
• Currency. Mirror the currency and exchange rate the invoice used, not the rate on the day you raise the credit. Otherwise the pair will never reconcile.

Digital goods have one advantage here. Refunds usually arrive within days, often inside the same VAT period, so the adjustment and the sale cancel out in the same return.

Issuing credit notes without the manual work

Knowing what a credit note is takes five minutes. Issuing them by hand is the actual cost:

• Matching each one to the invoice it corrects.
• Mirroring the tax treatment and currency.
• Keeping a separate number sequence.
• Making sure the adjustment lands in the right return period.

That is the work Quaderno removes:

• Credit notes are generated against the invoice they correct, carrying its tax treatment and currency across.
• Numbering stays sequential on its own series.
• The adjustment lands in the tax reports for the period you issued it.
• Refunds processed in a connected payment gateway create the credit note automatically. The support guide on creating a credit note covers the steps in the app.

If the invoice you are correcting was a cross-border sale, the VAT treatment depends on how that sale was reported. Our guide to preparing a VAT return covers where the adjustment ends up.