A credit note is the official way to say "I billed you too much" — without deleting or editing the original invoice. It's a document that reduces what a client owes (or records that you owe them money back), always tied to a specific invoice. The golden rule it exists to protect: never alter an invoice you've already sent. Issued invoices are records; credit notes are the corrections.
When a credit note is the right tool
Overcharges and billing errors. You billed 14 hours when the timesheet says 11, applied the wrong rate, or duplicated a line. The invoice is out; the client may have already entered it into their system. A credit note for the difference fixes the amount while leaving the original intact.
Returns. A client returns goods, or rejects part of a delivery. The credit note records the value coming back off their account.
Cancellations and partial cancellations. A project is cancelled after invoicing but before (or partway through) delivery. A credit note for the undelivered portion — or the full amount — closes it out cleanly.
Agreed discounts after the fact. You resolve a quality complaint by knocking 15% off. The original invoice stands; the credit note records the goodwill reduction with a paper trail.
What a credit note is not for: fixing a typo in an address or a wrong due date on an unpaid invoice nobody has processed yet. If the client confirms they haven't recorded it, you can void and reissue. Once an invoice is in anyone's books, correct with a credit note.
Why not just edit or delete the invoice?
Because both sides keep records, and those records must agree. If you quietly reissue INV-0231 with a smaller total, the client's bookkeeper now holds a document that doesn't match the one in their system — and your own numbering tells an inconsistent story. In VAT/GST systems this matters even more: the tax on the original invoice was recorded by both parties, and the credit note is the document that formally reverses the right portion of it. Credit note out, both ledgers adjust, everything reconciles.
The mechanics: what goes on a credit note
A credit note mirrors the invoice it corrects:
| Field | What to put there |
|---|---|
| Title | "Credit Note" — prominently, so it's never mistaken for a bill |
| Credit note number | From its own sequence (see below) |
| Original invoice reference | "Issued against invoice INV-0231, dated 4 Sep 2026" — this is mandatory in practice |
| Line items | Only the lines being credited, at the amounts being credited |
| Tax | Same tax label and rate as the original, applied to the credited amount |
| Notes | The reason: "3 hours billed in error", "goods returned 18 Sep" |
Show the credited amounts the same way the original showed the charges — the document's title does the sign-flipping. A credit note totaling $360 means $360 comes off what the client owes.
How the money resolves depends on payment status. Original invoice unpaid: client pays the invoice total minus the credit note. Already paid: you either refund the amount or, by agreement, carry it as credit against their next invoice ("credit applied to INV-0240"). Say which, on the credit note itself.
The negative-line alternative. For small corrections with a client you bill regularly, some businesses skip the separate document and add a negative line to the next invoice: "Credit — 3 hours overbilled on INV-0231 … −360.00". This is legitimate and clients understand it, but it only works when there is a next invoice soon. A standalone credit note is the cleaner, more universal instrument.
Numbering credit notes
Give credit notes their own sequence, prefixed so they can never be confused with invoices: CN-0001, CN-0002, and so on — sequential, no gaps, exactly like your invoice numbers. Don't issue them from your invoice sequence (a "missing" invoice number that turns out to be a credit note confuses every audit trail), and don't improvise per-invoice numbering like INV-0231-CREDIT once you issue more than a couple a year. Two clean parallel sequences — INV- and CN- — and every document cross-references its counterpart.
Example: credit note for overbilled hours
A credit note issued against a specific invoice, from its own CN- sequence, stating the reason and how the credit will be settled.
Keep corrections boring
The best credit note is unremarkable: it names the invoice, states the reason, shows the math, and both ledgers move on. Set up your CN- sequence before you need it, and corrections stop being awkward emails and become routine paperwork.
You can produce a credit note the same way you produce an invoice — the free invoice generator lets you set the document number to your CN- series, spell out the reference and reason in the notes and terms fields, and download the PDF with no signup or watermark. For the document that starts the story rather than corrects it, see What Is an Invoice?.