Apology Email for a Late or Wrong Invoice
Apology email for a wrong or late invoice: 8 templates for billing errors, overcharges, duplicates and delays, plus how to correct the invoice properly.
You sent an invoice with the wrong amount, the wrong client name, or two weeks after the work finished. An apology email for a wrong or late invoice should do three things quickly: own the mistake in one sentence, tell the client what to do with the incorrect invoice, and deliver the correction. The eight templates below cover the most common billing errors, and the guide explains how to fix the invoice itself so your records stay clean.
The three parts of a good billing apology
- Acknowledge: name the error precisely. "Invoice INV-1042 showed 20 hours instead of 12" is better than "there was a mistake".
- Instruct: tell the client whether to ignore, delete or keep the original, and whether they need to do anything in their system.
- Correct: attach the corrected document and restate the right amount and due date.
Avoid long explanations of how the error happened, blaming software or colleagues, and over-apologising. Clients mostly want to know what they owe now.
Correcting the invoice: credit note or reissue?
The email is the easy part. The invoice correction needs to follow a method that keeps your numbering and tax records consistent. Our guide on how to correct an invoice covers every option in detail; this summary matches common errors to fixes.
| Error | Usual fix |
|---|---|
| Typo in client address, invoice not yet recorded | Send a corrected copy with the same number, clearly marked as corrected |
| Overcharge (wrong hours, rate or quantity) | Issue a credit note for the difference, or credit in full and reissue |
| Undercharge | Issue a supplementary invoice or debit note for the difference |
| Wrong client entirely | Credit note to cancel in full, then new invoice to the right client |
| Same invoice sent twice | Confirm which number stands; cancel the other |
| Invoice created in error, never sent | Void the invoice in your records, keeping the number |
For VAT-registered UK businesses, HMRC's general VAT guide explains how to adjust VAT through credit notes when the value of a supply changes (VAT Notice 700, section 18). This is general information, not tax advice; check the rules for your country or ask an accountant. The difference between a credit memo and a credit note is mostly terminology, but use the term your client's AP team expects.
Worked example: overcharged hours
A consultant billed 20 hours at 95.00 instead of 12 hours. The client has already logged the invoice.
| Document | Calculation | Amount |
|---|---|---|
| Original invoice INV-1042 | 20 h x 95.00 | 1,900.00 |
| Correct charge | 12 h x 95.00 | 1,140.00 |
| Credit note CN-014 (refers to INV-1042) | 1,900.00 - 1,140.00 | -760.00 |
| Net amount the client owes | 1,900.00 - 760.00 | 1,140.00 |
If the client had already paid 1,900.00, they would be owed 760.00, which you can refund or set against their next invoice.
Apology email templates for a wrong or late invoice
1. Overcharge (credit note)
Subject: Correction to invoice INV-1042: credit note attached
Hi Sam,
I am sorry: invoice INV-1042 billed 20 hours for March, but the correct figure is 12 hours. I have attached credit note CN-014 for USD 760.00, which reduces the balance on INV-1042 to USD 1,140.00. The due date of 2 April is unchanged. Apologies for the extra step on your side.
Best regards,
Ana
2. Wrong client name or address
Hi Priya,
Apologies, invoice INV-2001 was addressed to your previous company name. Attached is a corrected copy with the same number and amount, addressed to Northgate Business Park Ltd. Please replace the earlier version in your records. Nothing else has changed.
Tom
3. Invoice sent to the wrong client
Dear Mr Hughes,
Earlier today I sent you invoice INV-5121 in error; it was intended for another client. Please delete it and do not pay it. I have cancelled it with a credit note on our side, and your correct invoice, INV-5120, is attached. I apologise for the confusion.
Jamie Park
4. Duplicate invoice sent
Hi Kate,
You received invoice INV-1063 twice this week, once on Monday and again today as INV-1064, because of a sending error on my side. Please process INV-1063 only; INV-1064 has been cancelled. Sorry for any confusion. Our guide to duplicate invoice copies explains how we label genuine copies in future.
Ben
5. Undercharge (supplementary invoice)
Hi David,
I owe you an apology and an explanation. Invoice INV-1078 left out the stock photography licence we agreed on 2 October (USD 180.00). I have attached a separate invoice, INV-1080, for that amount only, with the usual 30-day terms. I am sorry it was not on the original.
Sara
6. Wrong tax rate
Hi Omar,
Invoice INV-0981 applied VAT at the wrong rate. I have issued credit note CN-021 cancelling it in full and attached a replacement, INV-0985, for AED 3,675.00 (3,500.00 plus 5% VAT of 175.00). Please process the replacement only. My apologies.
Noor
7. Late invoice
Hi Lena,
Please accept my apologies for the delay in sending this invoice for the work completed in September. Invoice INV-4110 for USD 2,250.00 is attached. To be fair to you, payment is due 30 days from today, on 12 December, rather than from the completion date.
Mike
8. Client already paid the wrong amount
Hi Sam,
Thank you for paying invoice INV-1042 so quickly. Unfortunately it overstated the hours, so you paid USD 760.00 more than you owed. I have issued credit note CN-014. Would you prefer a refund of USD 760.00 to your account, or for it to be deducted from April's invoice? Either is fine on my side.
Ana
How to handle an invoice mistake, step by step
- Confirm the error against the contract, timesheet or delivery note.
- Choose the correction method from the table above.
- Create the documents: credit note, corrected invoice or supplementary invoice. Our invoice generator lets you produce a clean replacement in minutes.
- Send the apology email with all documents attached in one message.
- Update your records so your ledger shows original, credit and replacement linked by reference.
- Fix the cause: a template error, a wrong saved rate or a missing review step. Keep your invoice numbering system intact throughout.
If the client spotted the mistake before you did, the first reply sets the tone; see how to reply to an invoice query for wording that works before you have checked the facts.
Should you apologise by phone first?
For small errors, email alone is fine and gives the client a written record. For bigger ones, such as an invoice sent to the wrong client, a large overcharge, or an error the client has already paid, a short call first shows you take it seriously. Keep the call brief, explain the fix and say the documents are on their way, then send the email immediately so the AP team has the paperwork. Never rely on the call alone: the client accounts team needs the credit note and corrected invoice in writing.
Apology phrases to use and avoid
| Use | Avoid | Why |
|---|---|---|
| "I am sorry: invoice INV-1042 showed the wrong hours." | "Sorry for any inconvenience this may have caused." | Specific beats generic |
| "Please disregard INV-5121 and do not pay it." | "Please ignore the previous email." | Names the exact document |
| "The corrected total is USD 1,140.00, due 2 April." | "The figures should be right now." | States the outcome |
| "I have added a second check before invoices go out." | "This will never happen again." | A real fix, not a promise |
| "Our system applied last year's rate." | "My assistant messed it up." | Owns the mistake without blame |
A pre-send checklist to prevent billing errors
Most invoice mistakes come from a handful of fields. Check these before every send:
- Client legal name and address match the contract or PO.
- Quantities and hours match the timesheet or delivery note.
- Rates match the current agreement, especially after a price change.
- Tax rate is right for the client's location and the type of supply.
- Deposits and earlier payments have been deducted.
- Invoice number is the next in sequence and not reused.
- Recipient email is the client's billing address, not another client with a similar name.
A two-minute check against this list costs far less than an apology email, a credit note and a delayed payment.
Mistakes to avoid
- Silently sending a "new" invoice with no explanation, which can lead to both being paid.
- Deleting the wrong invoice from your records and leaving a numbering gap.
- Changing the amount on an invoice already recorded instead of crediting it.
- Restarting payment terms without saying so, or failing to extend them when the delay was yours.
- Over-explaining: one sentence of apology is enough.
Fewer errors start with a clear template. Build your next invoice in our invoice generator, which totals each line for you and exports a PDF, with no sign-up required.
Frequently asked questions
How do I apologise for sending the wrong invoice?
Acknowledge the error in one sentence, explain what was wrong without excuses, and tell the client exactly what to do with the incorrect invoice. Then send the correction, either a credit note and new invoice or a corrected copy, depending on your process. For example: "Invoice INV-1042 showed 20 hours instead of 12. Please disregard it; I have attached credit note CN-014 and corrected invoice INV-1043."
Should I edit and resend the original invoice or issue a credit note?
If the client has not recorded the invoice and you are not VAT or GST registered, some businesses simply cancel and reissue it with a note. Once an invoice has been sent and recorded, or where VAT or GST is involved, the cleaner route is a credit note that cancels all or part of the original, followed by a new invoice if needed. This keeps your invoice numbering complete and your tax records accurate.
How do I apologise for a late invoice?
Keep it brief and focus on making payment easy. Apologise once for the delay, confirm the invoice details, and if the delay shortens the client's payment window, offer the normal terms from the date you sent it. For example: "Apologies that this invoice for October is reaching you late. Payment is due 30 days from today, on 12 December."
What if the client already paid the wrong invoice?
If they overpaid, apologise and offer a choice: a refund of the difference or a credit applied to their next invoice. State the exact amount, show the calculation and confirm in writing which option they chose. If they underpaid because of your error, issue a supplementary invoice or debit note for the difference and give them normal payment terms for it.
Do I need to apologise for an invoice error at all?
A short apology is good practice when the mistake was yours, because it costs the client time to process and correct. It does not need to be long or emotional. One clear sentence, a quick fix and steps to prevent it recurring usually matter more to a client than elaborate wording. If the client was responsible for the error, you can simply explain the correction without apologising.
Invoice Creator Editorial Team
Guides on invoicing, cash flow and small-business finance from Invoice Creator, operated by Next Software Development Company. Content is reviewed for accuracy against the fields our own invoice generator produces.
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