How to Correct a Mistake on an Invoice
If you have already sent the invoice, do not quietly edit it. Issue a corrected invoice or a credit note so your records and your customer's records stay aligned.
In this answer
- Know whether to fix before or after sending
- Choose between a reissue and a credit note
- Handle GST corrections properly
- Find out where to confirm the rules
4 min
Before vs after you send
How you fix an invoice depends on whether it has left your hands. If you spot the error before sending, simply correct the draft and send the right version — no harm done. The problem only arises once the invoice has been issued to the customer, because at that point it is part of both parties' records.
The cardinal rule after sending is: do not silently change the original. Editing an issued invoice creates two different versions of the same document floating around, which is a recipe for confusion and disputes. Instead, use a transparent correction that leaves a clear trail of what changed and why.
Reissue or credit note
There are two clean ways to correct an issued invoice. You can cancel and reissue: clearly cancel the original and provide a corrected invoice with a new number, referencing the one it replaces. Or, where you are reducing an amount that was over-billed, you can issue a credit note against the original to offset the excess.
Which you pick depends on the error. A wrong total or quantity often calls for a corrected invoice; an over-charge or partial return often suits a credit note. Either way, the original and the correction should reference each other so anyone reading the file can follow the story. See how to issue a credit note for that route.
When GST is involved
If the mistake affects a sale that included GST, the correction also changes the GST you accounted for, so it needs to be handled with that in mind. Reducing an amount may call for an adjustment note; other corrections may flow through differently. The ATO sets out how GST corrections should be documented and reflected on your activity statement. Because getting the GST side wrong can misstate what you owe or are owed, confirm the right approach with the ATO or your accountant whenever a correction touches a GST sale.
Keep it tidy
Produce the corrected invoice or credit note with our free invoice tools, and keep both the original and the correction on file together.
This is general information only, not tax or legal advice. Invoice correction and GST adjustment rules depend on your circumstances — confirm them with the ATO or your accountant.
Key takeaways
- Fix freely before sending; never silently edit a sent invoice.
- Cancel and reissue, or issue a credit note, to correct an issued invoice.
- Make the original and the correction reference each other.
- GST corrections may need an adjustment note.
- Confirm the right approach with the ATO or your accountant.
Frequently asked questions
Can I just edit and resend the same invoice?
Not once it has been sent. Cancel and reissue with a new number, or use a credit note, so there are not two conflicting versions.
Which is better, a reissue or a credit note?
It depends on the error. Wrong totals often suit a corrected invoice; over-charges often suit a credit note. Either way, reference the original.
What if the mistake changes the GST?
Then the correction affects the GST you accounted for and may need an adjustment note. Confirm the approach with the ATO or your accountant.
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