Getting paid

Credit Notes and Refunds: Correcting an Invoice

Everyone sends a wrong invoice eventually — the wrong quantity, the wrong rate, work that was returned, a client who paid twice. The instinct is to fix the original and resend it, and that instinct is wrong in every accounting system in the world. A sent invoice is a record of something that happened. You do not revise history; you record the correction alongside it. This guide covers how, and what it does to your tax.

By Arshad Hossain · Published 16 August 2026

The short version

Never edit or delete a sent invoice. Issue a credit note against it.
A credit note needs its own number, and must reference the invoice it corrects.
A refund and a credit note are different things — one moves money, one adjusts a balance.
Correcting an invoice usually adjusts your tax position for the period it is issued in.

Why you never edit a sent invoice

Once an invoice leaves your hands it exists in two sets of books, not one. Your client has recorded it as a payable, possibly claimed input tax on it, and possibly already scheduled it for payment. Editing your copy creates a mismatch that neither of you can reconcile.

It also breaks your numbering integrity. Sequence gaps and altered documents are exactly what tax authorities look for when testing whether invoices have been suppressed, and "I just corrected it" is a difficult explanation to make convincingly two years later.

The correct mechanism is an adjustment document that references the original: a credit note to reduce the amount, or a debit note to increase it. The original stands, the correction is recorded, and both sets of books can be reconciled.

The one exception is an invoice you have not sent. If it is still a draft on your machine, edit it freely — nothing is a record until it has been issued.

Credit note, debit note, refund

Three different instruments, frequently confused, doing three different jobs.

A credit note reduces the amount a client owes. Use it when you overcharged, when goods were returned, when a discount was agreed after invoicing, or to cancel an invoice entirely. It does not move money — it adjusts the balance.

A debit note increases the amount owed, or is used by a buyer to notify a supplier of an intended reduction. Where you undercharged, some businesses issue a debit note and others simply issue a supplementary invoice; both are acceptable provided you are consistent.

A refund moves money back to the client. It is what happens after a credit note when the client has already paid and there is no future work to set the credit against.

The sequence for an overpaid, overcharged invoice is: credit note reducing the balance, then a refund of the resulting negative balance. Skipping the credit note and just sending money back leaves your books showing income you did not keep.

Situation	Instrument	Money moves?
Overcharged, not yet paid	Credit note	No
Overcharged, already paid	Credit note, then refund	Yes
Undercharged	Debit note or new invoice	No, increases balance
Goods returned	Credit note	Only if already paid
Invoice issued in error	Credit note cancelling it in full	No
Client paid twice	Refund, or credit against next invoice	Usually yes
Discount agreed late	Credit note	No

What a credit note must contain

A credit note is a formal document in most tax systems, with required particulars much like an invoice.

The words "Credit Note" clearly displayed
Its own unique number, from its own sequence or your invoice sequence
The date of issue
Your details and the client's, exactly as on the original invoice
The number and date of the invoice being corrected
The reason for the credit
The lines being credited, with quantities and values
The tax being reversed, at the same rate as the original
The total amount credited

The tax consequences

A credit note changes your tax position, and the timing matters.

In most VAT and GST systems, an adjustment is accounted for in the period the credit note is issued, not the period the original invoice was raised. You do not go back and amend a filed return; you reflect the adjustment in the current one.

The tax reversed must be at the rate originally charged, even if rates have since changed. A 2024 invoice credited in 2026 reverses at the 2024 rate.

Your client makes the mirror adjustment, reducing the input tax they claimed. This is why issuing the credit note promptly matters — a client who claimed input tax on an invoice you later canceled is carrying an error until you give them the document that lets them fix it.

For overpayments specifically, money a client has paid that you are not entitled to keep is not income. Holding it indefinitely is neither good practice nor, in many jurisdictions, lawful — unclaimed balances eventually fall under specific rules about what must be done with them.

Credit note and refund questions, answered

What is a credit note?

A document that reduces the amount a client owes against a previously issued invoice. It references the original invoice, states the reason and reverses the relevant tax. It adjusts a balance rather than moving money.

Can I just delete or edit an invoice I sent by mistake?

No. It exists in your client's books as well as yours, and possibly in a tax return already filed. Issue a credit note cancelling it in full, referencing the original number. Editing sent invoices also breaks the numbering integrity auditors check.

What is the difference between a credit note and a refund?

A credit note adjusts what is owed; a refund moves money back. If the client has not paid, a credit note alone is enough. If they have paid and there is no future work to offset, you issue the credit note and then refund the balance.

What is a debit note?

A document increasing the amount owed, used where you undercharged, or issued by a buyer to notify a supplier of a claimed reduction. Some businesses simply raise a supplementary invoice for undercharges instead; either works if applied consistently.

Does a credit note need its own number?

Yes. It is a formal document requiring a unique reference, either from its own sequence or continuing your invoice sequence. It must also carry the number and date of the invoice it corrects, so the two can be matched.

How do I cancel an invoice completely?

Issue a credit note for the full value, referencing the original invoice number and stating the reason. The invoice and the credit note both stand in your records and net to zero. Never reuse the canceled invoice number for a different sale.

What do I do if a client overpays?

Tell them immediately — do not wait to be asked. Then either refund the excess or, with their agreement, hold it as a credit against the next invoice. Money you are not entitled to keep is not income, and holding it silently is a genuine problem.

Can I offset a credit note against a future invoice?

Yes, with the client's agreement, and it is often simpler than a refund for an ongoing relationship. Show the credit as an explicit deduction on the next invoice referencing the credit note number, so both sides can reconcile the sequence.

When should a credit note be issued?

As soon as you know the invoice is wrong. Delay causes real problems for the client, who may have claimed input tax on an invoice that should not stand and cannot correct it until you give them the document.

How does a credit note affect my VAT return?

It reduces your output tax in the period the credit note is issued, not the period of the original invoice. You do not amend a filed return. The reversal uses the rate originally charged, even if rates have changed since.

Do I need to give a reason on a credit note?

Yes, and it should be specific — "goods returned", "invoiced in error", "agreed discount". Vague reasons attract questions during review, and a clear reason also helps your client's bookkeeper apply the adjustment correctly at their end.

What if a client refuses to accept a credit note?

A credit note in their favour is rarely refused, but it happens where the client believes the credit should be larger. Issue what you accept is due, keep the correspondence, and treat the remaining disagreement as a dispute in its own right.

Frequently Asked Questions

Is a credit note the same as a refund receipt?

No. A credit note adjusts the invoiced balance; a refund receipt evidences money actually returned. Where a paid invoice is credited and refunded, you may end up with both, and both belong in your records.

Can I issue a credit note years after the invoice?

Generally yes, though the practicalities get harder — your client may have closed the relevant period, and tax rules may limit how far back adjustments can be reflected. Correct errors as soon as they are found rather than letting them age.

Do I need a credit note for a discount given at the time of invoicing?

No. A discount agreed before the invoice is issued goes on the invoice as a discount line. A credit note is only needed for a reduction agreed after the invoice has already been issued.

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