You hit send, then you see it. The rate is wrong, the client's business name is misspelled, tax is missing, or you billed the same project twice. Your first instinct is usually the worst one: open the invoice, quietly fix the number, and pretend the original never existed.
Sent invoices are business records. Once one leaves your hands, it exists in two places (yours and your client's), and silently editing your copy means the versions no longer match. This guide covers the three clean ways to correct a sent invoice and which fix matches which mistake.
The quick version
Can you change an invoice after sending it? Not by editing or deleting it. The professional fix depends on payment status:
- Unpaid (or unsent internally) and the client agrees: void the original and reissue a corrected invoice with a new number that references the old one.
- Already paid or partially paid: leave the original alone and issue a credit note for the difference (or a refund plus a credit note documenting it).
- You undercharged: the original stands; send a supplemental invoice for the missing amount with a short, factual explanation.
In every case the original invoice stays in your records, and a new document corrects it. That is what keeps your numbering sequence and audit trail intact.
Why you never delete or overwrite a sent invoice
Deleting a sent invoice creates three problems at once.
Your records stop matching your client's. Your client already has Invoice #INV-0231 for $2,400 in their inbox. If you silently change your copy to $2,100, there are now two documents with the same number and different totals. To an accountant or tax authority reviewing either side later, mismatched duplicates look like manipulation even when the intent was innocent.
Your numbering breaks. Sequential invoice numbers are the backbone of a clean audit trail. Delete INV-0231 and your sequence jumps from 0230 to 0232, and a gap in a numbered series invites exactly the question you do not want: what happened to the missing one?
You lose the history. Invoices are records you generally need to keep for years (see how long to keep receipts and invoices). A void, credit note, or supplemental invoice tells the full story later: what was billed, what was wrong, and how it was fixed. A deletion tells no story at all.
There is also a payment cost. An invoice with an error almost always gets set aside instead of paid, and the late pile is already deep: 47% of US small businesses report invoices already more than 30 days past due (Intuit QuickBooks, 2025). The faster you issue a clean correction, the faster it gets back in the payment queue.
The three fixes at a glance
| Situation | Payment status | The fix | What happens to the original |
|---|---|---|---|
| Wrong amount, details, or tax; client agrees | Unpaid | Void and reissue with a new number | Marked "VOID," kept on file |
| Overcharge or error discovered | Paid or partially paid | Credit note for the difference | Stays valid, credit note adjusts it |
| Undercharge or missing line item | Any | Supplemental invoice for the balance | Stays valid and unchanged |
Fix 1: Void and reissue (unpaid, client agrees)
This is the cleanest correction when no money has moved yet:
- Contact the client first. A quick message: "I spotted an error on Invoice #INV-0231. Please disregard it. A corrected invoice is on its way."
- Mark the original as void. Do not delete it. Write "VOID" on your copy, note the date and reason ("rate error, replaced by INV-0232"), and keep it in your records.
- Issue the corrected invoice under the next number in your sequence. Not the same number. INV-0231 was voided, so the replacement is INV-0232.
- Reference the old invoice on the new one. One line in the notes field does it: "Replaces Invoice #INV-0231, issued in error."
Example: you billed a consulting client $3,600 for 24 hours when the timesheet shows 21. The client has not paid. You void INV-0231, send INV-0232 for $3,150 with the replacement note, and both documents survive in your files with no gaps in the sequence.
Void-and-reissue is also the right move for wrong client details, since a misspelled legal name or outdated billing address can get an invoice rejected by a client's accounts-payable system. (For what those details should be, see what to include on an invoice.)
Fix 2: Credit note (already paid or partially paid)
Once money has moved, voiding no longer works, because the original invoice is now attached to a real payment. The original must stand, and a second document adjusts it: a credit note.
Say a client paid Invoice #INV-0240 in full at $1,800, and you later realize a $200 line item was billed twice. You issue a credit note for $200 referencing INV-0240. That $200 either goes back to the client as a refund or sits as a credit against their next invoice. Either way, the invoice, the credit note, and the payment records all line up.
Partial payments work the same way. If the client paid $900 of the $1,800 before you caught the $200 error, the credit note reduces the outstanding balance from $900 to $700.
The mechanics, numbering, and refund-versus-credit decisions are covered in what is a credit note, and you can create one in a minute with the free credit note generator.
Fix 3: Supplemental invoice (you undercharged)
Undercharging feels awkward: you are asking for more money after the client thought the bill was settled. The mechanics are simple: the original invoice stays as it is, and you issue a new invoice, with its own number, for the amount you missed.
The wording is what protects the relationship. Three rules:
- Be factual, not groveling. State what was missed and why the new invoice exists.
- Reference the original. "Supplemental to Invoice #INV-0245" belongs on the new invoice.
- Send it fast. An undercharge caught within a week reads as an honest slip. One surfacing three months later reads as sloppy bookkeeping, and clients push back harder.
A message that works:
"Hi Dana, while reconciling this month I found that Invoice #INV-0245 left off the 6 hours of revision work from the week of April 14 ($720 at our agreed rate). Invoice #INV-0251 covers those hours and references the original. Apologies for the extra paperwork, and thanks for bearing with me."
If the amount is small and the client is long-term, some businesses absorb it and tighten their process. If you do bill it, a clear supplemental invoice beats an edited original every time.
The most common invoice mistakes, ranked
In rough order of frequency:
- Wrong amount. A stale rate, a quantity typo, or a math slip. Unpaid: void and reissue. Paid: credit note (overcharge) or supplemental invoice (undercharge).
- Wrong client details. Misspelled legal name, old address, wrong contact. Usually harmless between two freelancers, but corporate AP departments reject these. Void and reissue with correct details.
- Missing or incorrect tax. If you should have charged sales tax and did not, a supplemental invoice or corrected reissue fixes the paperwork, but sales tax rules vary by state and jurisdiction, so verify yours (see do freelancers charge sales tax). This is general guidance, not tax or legal advice.
- Duplicate invoice. You billed the same work twice. If neither is paid, void the duplicate and tell the client which number to pay. If both were paid, issue a credit note against the duplicate for the full amount and refund it promptly.
How numbering holds the audit trail together
Every fix above leans on one habit: each document gets its own number, and corrections reference the document they correct.
- A voided invoice keeps its number. INV-0231 stays INV-0231, marked void.
- A reissued invoice takes the next number in sequence and names the invoice it replaces.
- Credit notes run their own series (CN-0001, CN-0002...) and each one names the invoice it adjusts.
- A supplemental invoice is just the next invoice in your normal sequence, with a reference line to the original.
Follow that pattern and any reviewer can reconstruct exactly what happened from the documents alone, with no gaps and no orphaned numbers. If your current system is "whatever number feels right," fix that first: how to number invoices walks through simple formats that scale.
Corrections are also much easier when a replacement document takes two minutes instead of twenty. Invoity's free invoice generator lets you issue a corrected invoice or credit note with proper numbering and a notes field for the reference line, then download the PDF instantly, no signup to start. If a correction spans several billing periods, the Multiple-invoices option generates a properly numbered series across dates in one pass.
Frequently asked questions
Can I edit an invoice after I've sent it?
No, not the sent copy. Once delivered, your client holds a version of record, and editing yours creates two conflicting documents with the same number. Correct it with a new document instead: void and reissue if unpaid, a credit note if paid, or a supplemental invoice if you undercharged.
Is it illegal to change an invoice after sending it?
Quietly altering issued invoices can cross into falsifying business records, especially where tax is involved. Requirements vary by state and jurisdiction, so verify yours, and treat this as general guidance rather than legal advice. The safe path is the same everywhere: keep the original, void it or adjust it with a credit note, and let the paper trail show the correction.
What if the client already paid the incorrect invoice?
Leave the original invoice alone and issue a credit note for the difference, referencing the original invoice number. Settle the credit as a refund or as a credit toward the client's next invoice, whichever you both prefer. If you underbilled, send a supplemental invoice for the gap instead.
Should a corrected invoice have a new number?
Yes. The voided original keeps its number, and the corrected invoice takes the next number in your sequence with a note like "Replaces Invoice #INV-0231." Reusing the old number creates two different documents with one identity, which is exactly the ambiguity a numbering system exists to prevent.