Credit Note & Debit Note Under GST: How to Correct an Invoice
Written by Naresh, Founder of QWIK INVOICE · Last updated: 29 August 2026
The short answer: once a GST tax invoice is issued, you can't just edit or delete it. Corrections are documented through a credit note (reducing the invoice's value or tax) or a debit note (increasing it), both referencing the original invoice and both reported in your GST return.
Why can't I just fix the original invoice?
A tax invoice is a legal record the moment it's issued — both you and your customer may already have reported it (or be about to report it) in a GST return, and your customer may have claimed input tax credit based on it. Silently changing the numbers afterward would break that trail. GST law instead requires any adjustment to be issued as a separate, traceable document — a credit note or debit note — that clearly references the original invoice's number and date and states the reason for the change. This is set out in Section 34 of the CGST Act, 2017.
When do I issue a credit note?
A credit note is issued by the supplier to reduce the value or tax of a previously issued invoice. Common triggers: the customer returned some or all of the goods; you agreed to a discount after the invoice was already raised; the original invoice accidentally overcharged the customer; or there was a deficiency in the goods or service supplied. The credit note lowers what the customer owes (or refunds them) and correspondingly lowers your own output tax liability for that supply.
When do I issue a debit note instead?
A debit note is the opposite — issued by the supplier to increase the value or tax of a previously issued invoice. This typically happens when the original invoice undercharged the customer, for example if a quantity or rate was entered incorrectly and too little was billed. A debit note raises what the customer owes and correspondingly increases your output tax liability.
Credit note vs debit note at a glance
| Aspect | Credit Note | Debit Note |
|---|---|---|
| Direction of adjustment | Reduces invoice value/tax | Increases invoice value/tax |
| Typical trigger | Return, discount, overcharge, deficiency | Undercharge on the original invoice |
| Effect on supplier's tax | Output tax liability decreases | Output tax liability increases |
| Effect on buyer's ITC | Buyer generally must reverse the corresponding credit | Buyer may claim additional credit, subject to normal ITC conditions |
What has to be on a credit or debit note?
At minimum, it must reference the original invoice number and date, state a clear reason for the adjustment (return, discount, correction, etc.), and show the value/tax being adjusted. It follows much of the same structural discipline as a regular tax invoice — see our GST invoice format checklist for the fields a compliant document generally needs, and apply the same care to numbering it consecutively within its own series.
Is there a deadline for issuing a credit note?
Yes, and it's one of the more commonly missed rules. Credit notes that reduce a supplier's output tax liability generally have to be issued and reported by a cutoff tied to the end of the financial year the original supply was made in — broadly, by 30th November following that financial year, or before filing the relevant annual return, whichever comes first. This deadline has shifted with amendments over the years, so don't rely on a specific date from memory — confirm the current cutoff on the GST portal before issuing a credit note against an older invoice, especially one from a prior financial year.
What if the original was a proforma, not a real tax invoice?
Credit and debit notes only apply to real tax invoices. If you're correcting a preliminary quote or proforma that was never actually invoiced for GST purposes, you don't need either document — just issue a revised proforma. See our proforma vs tax invoice guide if you're unsure which category your original document falls into.
Practical steps to issue one correctly
- Reference the exact original invoice number and date — don't leave this vague.
- State the specific reason (return, discount, correction, deficiency, etc.).
- Number the credit/debit note consecutively within its own series, following the same discipline as regular invoices.
- Report it in the GST return for the period it's issued in — don't wait, and don't skip it because the adjustment feels minor.
- If reducing tax on an invoice from a prior financial year, check the issuance deadline before assuming it's still allowed.
QWIK INVOICE lets you duplicate or edit a saved invoice as a starting point for the numbers — but remember the actual credit or debit note you send still needs to explicitly reference the original invoice and follow the rules above; simply re-editing your saved copy isn't the same as issuing a proper adjustment document. Open the invoice generator to get started.
Frequently asked questions
What is a credit note in GST, with an example?
A credit note is a document a registered supplier issues to a buyer to formally reduce the value or GST charged on a previously issued tax invoice. For example, if you invoiced a customer ₹10,000 + GST and they later returned ₹1,000 worth of goods, you'd issue a credit note for ₹1,000 + the corresponding GST, referencing the original invoice number. It lowers what the customer owes and lowers your own output tax liability for that supply.
Can I just edit or reissue a GST invoice if I made a mistake?
No — once a tax invoice is issued, GST rules don't let you silently edit or delete it. Any correction has to be documented through a credit note (to reduce the invoice's value or tax) or a debit note (to increase it), both of which must clearly reference the original invoice number and date, and both of which need to be reported in your GST return for the period they're issued in.
What's the difference between a credit note and a debit note?
A credit note reduces the value or tax of a previously issued invoice — typically because goods were returned, a discount was agreed after the invoice was raised, the original invoice overcharged the customer, or there was a deficiency in what was supplied. A debit note does the opposite: it increases the value or tax of a previously issued invoice, typically because the original invoice undercharged the customer.
Can we issue a credit note without GST?
Yes, but it's a different document. A financial (or commercial) credit note simply adjusts an amount between you and the customer — for example, a goodwill discount — without changing the taxable value or GST charged, so it isn't reported in your GST returns and doesn't affect your output tax liability. A GST credit note under Section 34, by contrast, does adjust the tax and must be reported. If you want to actually reduce your reported tax liability, a financial credit note won't do that — you need the formal GST credit note.
Who can issue a debit note?
Under Section 34 of the CGST Act, only the registered supplier who issued the original tax invoice can issue a debit note against it — not the buyer. A buyer who wants to record a shortfall or dispute in their own accounting can note it internally, but that has no GST effect; only the supplier's debit note, reported in the supplier's GST return, carries statutory weight and adjusts tax liability.
Does a credit note affect the buyer's input tax credit?
Yes. If your customer already claimed input tax credit based on the original invoice, a credit note that reduces the tax amount generally requires a corresponding reversal of that credit on their side. This is exactly why the note has to be properly reported in GST returns on both sides — it isn't just a paperwork formality between you and the customer.
Is there a deadline for issuing a credit note?
Yes — credit notes that reduce output tax liability are generally subject to a cutoff tied to the financial year the original supply was made in, broadly by 30th November following that financial year or before filing the relevant annual return, whichever is earlier. This deadline has been adjusted by amendments over time, so confirm the exact current cutoff on the GST portal rather than assuming it, especially for older invoices.
How do I report a credit or debit note in my GST returns?
You report it in GSTR-1 (or the IFF, if you're on QRMP) for the period it's issued in, referencing the original invoice number — those details then flow into GSTR-3B, where a credit note lowers your net output tax liability and a debit note raises it. On the recipient's side, it shows up in their GSTR-2A/2B, and they need to make the matching input tax credit adjustment in their own return.
What section of GST law governs credit and debit notes?
Credit and debit notes are governed by Section 34 of the CGST Act, 2017, which sets out when each can be issued, what they must contain, and how they interact with the supplier's tax liability and the recipient's input tax credit. The GST portal and CBIC's published rules are the authoritative source for the current requirements.
Ready to put this into practice?
Create Your Invoice Free