Credit Notes Explained: When and How to Issue One

A credit note (or credit memo) is a formal document that reduces what a customer owes, usually because you overbilled, need to cancel part of a charge, or are applying an agreed adjustment after the original invoice was issued. It is not the same as editing a PDF and resending it: once an invoice has gone to the client, the adjustment should be a separate, traceable document.

In the US, the IRS expects you to keep supporting documents for your income, and lists invoices among them (IRS: What kind of records should I keep); a credit note is part of that record when it changes the amount you were paid. In the UK, HMRC sets specific rules for credit notes in VAT Notice 700, section 18.2, covered below.

When to use a credit note

After the invoice was already sent (or booked)

If the client or your accountant has recorded the original invoice, issue a credit note rather than changing or reusing the invoice number. That preserves an invoice audit trail.

Returns, refunds, or service failures

You are reversing part or all of a charge, which reduces what the client owes you (your accounts receivable).

Post-invoice discounts

If a discount was not on the original invoice but is now agreed, a credit note documents the reduction cleanly. For discounts agreed before you invoice, see invoice discounts.

Tax corrections

When tax was overcharged, a credit note is the usual way to correct it. Rules vary by country; see invoice tax compliance.

When not to use one

Mistakes on an invoice the client has not received yet: void it and reissue it, if your policy allows. See the void invoice template for when voiding is appropriate.
Normal partial payments: record the payment; you do not need a credit note unless you are also reducing what is owed. See partial payments.
An undercharge: a credit note only reduces an amount. To bill more, issue a debit note or a new invoice for the difference.
A wrong detail with no change in amount (such as the client's address): in some countries this calls for a corrective invoice rather than a credit note.

What to include on a credit note

Unique credit note number and date of issue
Your name, address and, if VAT-registered, your VAT number
Client name and address
Original invoice number and date
Reason for the credit (brief, factual)
Description and quantity of what is credited, matching how the original invoice was structured
Amount credited excluding tax, and the tax rate and tax amount credited, if the original charged tax
Remaining balance on the invoice after the credit

UK VAT rules. HMRC's VAT Notice 700 (paragraph 18.2.3, page last updated 25 June 2026) says that to be valid for VAT a credit note must reflect a genuine mistake, overcharge or agreed reduction, be issued within 14 days of the refund payment being made to the customer, give the customer a genuine entitlement to a refund or offset, and show the details above, including the VAT rate and amount credited in sterling and the number and date of the original VAT invoice. Paragraph 18.2.5 says to use the VAT rate that applied at the time of the original supply. A credit note issued without a VAT adjustment should say "This is not a credit note for VAT".

Mirror the field discipline you use when you write an invoice, or start from the credit note template.

Workflow tips

Link the credit note in your accounting system to the invoice it adjusts. If the client pays less after a credit, confirm they reference the updated balance in their remittance advice. For ongoing relationships, follow up on any amount still due; the free payment reminder templates give you a gentle, firm and final version.

Putting it into practice

Give credit notes a number that tells them apart from invoices, such as a CN- prefix, so anyone reviewing your records can trace adjustments without confusing them with new sales. Some businesses run a separate CN series; others use one counter for all documents with different prefixes, which is what InvoiceQuickly does. Either works if every credit note quotes the invoice it adjusts. See invoice number best practices.

When you issue a credit for a tax correction, ask your accountant how to record it: some jurisdictions also require an amended return. If you frequently adjust invoices after sending them, look at upstream causes: unclear scope, missing purchase orders, or wrong rates caught late in approval. Make sure anyone who talks to clients knows not to promise credits without telling whoever does the invoicing.

Working with accountants and auditors

Share credit notes in the same export as the underlying invoice at month-end. If you use accrual accounting, confirm with your bookkeeper whether the credit is recorded against revenue or a contra-revenue account (such as sales returns and allowances). For VAT or GST, ask which period the adjustment belongs in. In the UK, paragraph 18.2.6 says that where the credit note is not correcting an error already declared on a return, you make the VAT adjustment in the accounting period in which the price decrease occurs, which for a decrease is the period in which the refunded amount is paid to the customer. If credits are frequent, investigate quoting and approval workflows rather than treating write-offs as normal.

Credit notes in InvoiceQuickly

On Pro ($9/month), open a sent invoice, enter the credit amount and the reason, and InvoiceQuickly creates a credit note that quotes the original invoice number and reduces that invoice's balance. New credit notes use their own CN- counter, separate from invoices and estimates. Historical gaps remain. The credit note has one credit line with no separate tax breakdown, and saved business tax IDs print on new documents, so if your tax authority requires the VAT credited and your registration number on the credit note, add them in the reason or use the credit note template. Invoices with a payment recorded can't be voided, so a credit note is how you reduce them.

See what's on Pro.

Credit notes vs other adjustments

Document type	When to use	Tax effect
Credit note	Reduces or reverses an invoice already issued	Reduces the tax charged, in proportion to the amount credited
Refund	Returns money already paid	The money movement; in the UK the VAT adjustment is made with a credit note
Debit note	Increases the amount owed on an invoice already issued	Tax charged only on the increase
Void	Cancels an invoice before the client has received or acted on it	None if it never reached the client; once a VAT invoice has been received, reverse it with a credit note
Discount on invoice	Reduces the price before you send the invoice	Tax calculated on the lower amount from the start

Credit notes are accounting documents that reverse or adjust previously issued invoices. They're not refunds (which move money) or voids (which cancel a document that should never have counted).

Step-by-step: Issuing a credit note

Step 1: Verify the underlying reason

Common reasons: scope changes, partial cancellation, billing errors, returned goods, agreed discounts, refunds of prepayments. Write the reason on the credit note.

Step 2: Reference the original invoice

Include the original invoice number and date, the credit note's own number and date, the reason, the amount credited and, if tax applies, the breakdown by tax rate.

Step 3: Apply the correct tax treatment

If the original invoice charged tax, the credit note reduces the tax in the same proportion, at the rate that applied to the original supply. In the UK, HMRC lets you skip the VAT adjustment only where the customer can reclaim all the VAT and you both agree not to adjust (Notice 700, paragraph 18.2.1).

Step 4: Send to the client (and refund if needed)

Email the credit note PDF to the client. If the invoice was already paid, refund the difference or agree to offset it against a future invoice, and process any refund through the payment method used.

Step 5: Record it in your accounts

A credit note reduces accounts receivable. If the invoice was already paid, it leaves a credit balance you owe the client until you refund or offset it.

Common credit note scenarios

Scope reduction mid-project: you invoiced $5,000 for 5 deliverables at $1,000 each. The client decides they only need 3. Issue a credit note for $2,000 for the 2 cancelled deliverables. The original invoice stands; the credit note brings the amount owed to $3,000.

Returned goods: a customer returns a $100 product. Issue a credit note for $100. If they already paid, refund the $100 as well.

Billing error with VAT (UK): you invoiced 11 hours at £100 (£1,100 plus 20% VAT of £220, total £1,320), but only 10 hours were worked. Issue a credit note for 1 hour: £100 plus £20 VAT, £120 in total. The net amount owed becomes £1,200 (£1,000 plus £200 VAT).

Prepayment refund: a customer prepaid $2,000 and the project is cancelled. Refund the $2,000 and issue a credit note against the prepayment invoice to record the reversal.

Frequently Asked Questions

Are credit notes required for refunds?

Not in every case, but a credit note is the standard way to document one. In the UK, if the refund changes the VAT you charged, you should issue a credit note, and HMRC says it must be issued within 14 days of the refund payment to be valid for VAT. Without one, your records show a sale and a payment out with nothing linking them.

What happens to VAT on credited amounts?

The VAT is reduced in proportion to the amount credited, at the rate that applied to the original supply. In the UK, unless you are correcting an error already declared on a return, you make the adjustment in the VAT period in which the refunded amount is paid to the customer (Notice 700, paragraph 18.2.6), and your customer reduces the input tax they claimed.

Should credit notes have their own numbering?

They need their own identifying number, and most businesses use a CN- prefix so credit notes can't be confused with invoices. A separate CN series is common, but one counter with different prefixes also works, as long as each credit note quotes the invoice it adjusts. Never reuse an invoice number.

Can I use a credit note for a full refund?

Yes. A credit note for the full amount reduces the invoice to zero. If the client had paid, also refund the money or agree to offset it.

How long should credit notes be retained?

As long as your invoices. In the US, the IRS's general rule is 3 years, with longer periods in some cases, such as 6 years if income was under-reported by more than 25% and 7 years for a bad debt deduction (IRS: How long should I keep records). Other countries set their own periods, often longer, so check with your tax authority. This is general information, not tax advice.