An invoice goes out with the wrong amount. Goods come back. A discount gets agreed after the fact. The instinct is to open the invoice and correct it, and that is the one thing you should not do.
Once an invoice has been sent to a customer or reported in a return, it is a record. You correct a record by adding to it, not by rewriting it. That is what credit and debit notes are for.
The short version
| Document | Use it when | Effect |
|---|---|---|
| Credit note | You charged too much, or goods came back | Reduces what the customer owes |
| Debit note | You charged too little | Increases what the customer owes |
Both reference the original invoice. Both carry their own number and date. Neither changes the invoice they correct.
When to issue a credit note
- Goods were returned, in full or in part.
- The invoice overstated the quantity, the rate or the tax.
- A discount was agreed after the invoice went out.
- A service was cancelled after being billed.
- The invoice was raised in error and needs cancelling entirely.
The credit note reverses the tax in the same proportion as the original. If you charged 18% split as CGST and SGST, the credit note reverses it the same way. Getting that wrong leaves your return inconsistent with the customer’s.
When to issue a debit note
Less often, but the same logic in reverse. You billed ten units and delivered twelve. The rate on the invoice was below what was agreed. Tax was applied at 12% when the correct slab was 18%.
You do not raise a second invoice for the difference. You raise a debit note against the original, so the two documents read as one corrected transaction.
A credit note is not a refund
This trips people up constantly. The credit note is the paperwork. The refund is the money moving.
You can raise a credit note and send the money back. You can also raise one and leave the value sitting on the customer’s account, reducing their next invoice. Both are normal. The credit note is required either way, because it is what makes the adjustment part of the record.
If you refund money without issuing a credit note, your books show a payment out with nothing explaining it.
What a credit note has to carry
- Your name, address and GSTIN.
- The customer’s name, address and GSTIN.
- A serial number from its own series, and a date.
- A reference to the original invoice and its date.
- The taxable value being credited and the tax, split the same way as the original.
The reference to the original invoice is the part people skip, and it is the most important one. A credit note that does not say what it corrects is very hard to explain a year later.
Timing matters
There are deadlines on when a credit note can still be reported against the original supply, tied to the annual return and the September following the financial year. Miss it and the adjustment may no longer reduce your tax liability, even though the commercial credit still stands.
The practical advice is simply not to sit on them. Raise the credit note when the return happens or the correction is agreed, not at year end when someone is tidying up.
Why editing the invoice is the worst option
It seems easiest. It is not. The customer already has the original, so now two versions of the same invoice number exist. If the original was reported in a return, your filing no longer matches your records. And there is nothing on file explaining why the amount changed.
A credit note takes about a minute and leaves a trail anyone can follow.
Pinvoice raises credit notes against the original invoice, reverses the tax the same way it was charged, and adjusts the customer’s balance automatically. See how credit notes work.
General guidance, not tax advice. Rules and time limits change. Check specifics with your accountant.