Credit note and debit note under GST: when to issue, time limits and ITC effect

Under Section 34 of the CGST Act, a supplier issues a credit note when an invoice overstated the value or tax, goods are returned, or the supply was deficient, and a debit note when the invoice understated the value or tax. Credit notes must be reported by 30 November after the financial year or the annual return date, whichever is earlier, and they reduce the buyer's input tax credit. This guide explains both documents, the deadlines, the return effect and a worked example.

Why you cannot just edit an invoice

Once a tax invoice is issued and reported, it is a permanent record. Your GSTR-1 has it, your buyer's GSTR-2B has it, and if you are under e-invoicing the IRP has a signed copy. GST law does not allow you to delete or overwrite it. Instead, Section 34 gives you two correcting documents: a credit note to reduce what the invoice said, and a debit note to increase it. Both are issued by the supplier, both reference the original invoice, and both flow through the returns so the government and the buyer see the same adjustment.

The contents are set by Rule 53(1A): your name, address and GSTIN; the nature of the document (credit note or debit note); a consecutive serial number of up to 16 characters, unique for the financial year; date; the recipient's name, address and GSTIN if registered; the serial number and date of the original invoice or invoices; the value of goods or services, rate of tax and amount credited or debited; and a signature. Since September 2019, one credit or debit note can cover several invoices.

When to issue a credit note

Section 34(1) lists three situations:

1. The taxable value or tax on the invoice exceeds what is actually payable. A pricing error, an agreed reduction, a wrong tax rate that was too high, or a discount given under Section 15(3)(b).
2. Goods are returned by the recipient. A sales return, whether partial or full.
3. The goods or services are found to be deficient. Damaged stock, short delivery, work not up to specification.

A credit note reduces your output tax for the month in which you declare it, and the second proviso to Section 34(2) makes that reduction conditional: it is allowed only to the extent the recipient has reversed the corresponding ITC, and never where the incidence of tax has been passed on to another person. In practice, if you issue a credit note to a registered buyer, they see it in GSTR-2B and must reduce their ITC; if they do not, your reduction can be questioned.

When to issue a debit note

Section 34(3) covers the mirror image: the taxable value or tax on the invoice is less than what is actually payable. Common triggers are a price escalation agreed after supply, additional quantity delivered, a tax rate that was applied too low, or a charge such as freight or installation that was missed on the invoice.

A debit note increases your output tax in the month you declare it, and the buyer can claim the additional ITC on it. Since 1 January 2021 the time limit for the buyer's ITC under Section 16(4) is linked to the date of the debit note, not the original invoice, so a debit note issued in July 2026 for an April 2025 invoice still gives the buyer usable credit. A supplementary invoice is treated the same as a debit note.

Time limits: the 30 November rule

For credit notes, Section 34(2) sets the outer limit: the note must be declared in the return for the month in which it is issued, and not later than 30 November following the end of the financial year to which the supply relates, or the annual return date if earlier. After the deadline you can still reduce the price commercially, but the GST you collected stays with the government.

Debit notes have no such cut-off because they increase tax, but interest runs from the original due date on the tax that was short-paid, so issue them promptly.

Effect on GSTR-1, GSTR-3B and the buyer

In your GSTR-1: credit and debit notes to registered buyers go in Table 9B (B2B), and those to unregistered buyers in Table 9B (B2CL) or as net figures in Table 7 for small B2C. Amendments to previously reported notes go in Table 9C. The original invoice number is entered against the note. Filing mechanics are in the GSTR-1 and GSTR-3B filing guide.

In your GSTR-3B: the net effect shows in Table 3.1(a). Since GSTR-3B is now auto-populated from GSTR-1 and largely locked for outward supplies, the note must be in GSTR-1 first.

For the buyer: a credit note appears in their GSTR-2B as a reduction, and they must reverse the ITC in Table 4(B) of their GSTR-3B. Under the Invoice Management System (IMS) on the portal, the buyer can accept, reject or keep the note pending before GSTR-2B is generated. If the buyer rejects a credit note, the supplier's liability is not reduced and the two parties need to sort it out before the next return. A debit note gives the buyer additional ITC, which they claim after it appears in GSTR-2B. The conditions for that credit are in input tax credit explained.

Sales returns

Sales returns are the most common credit note situation for traders. The key points:

• The credit note is issued by the original supplier, for the value and tax of the goods returned, referencing the original invoice.
• If the buyer is registered, some buyers instead raise a fresh tax invoice for the return, treating it as a sale back to you. Either approach is legally possible; the credit note route is simpler and keeps the deadline discipline.
• If the return relates to an invoice from a previous financial year, the 30 November deadline still applies to your ability to reduce tax, so old-stock returns in December onwards are commercial credit notes only.
• Goods moving back to you may need an e-way bill if the consignment value exceeds ₹50,000, with the reason "sales return" and the credit note as the document. See the e-way bill guide.

Post-sale discounts

A discount given after the sale is the second most common credit note case, and it has its own rule. Section 15(3)(b) allows a post-supply discount to reduce taxable value only if it was established under an agreement entered into at or before the supply, is specifically linked to the relevant invoices, and the recipient reverses the ITC attributable to it. Year-end volume discounts and target incentives that were agreed in writing at the start of the year meet this; an ad-hoc "we will knock off ₹10,000 because you are a good customer" does not, and for that you can issue only a commercial credit note without GST.

The GST Council in September 2025 recommended relaxing the "agreement before supply" condition so that post-sale discounts can be passed through GST credit notes with ITC reversal by the buyer, and the law was amended following that. Check the current text of Section 15(3)(b) and Section 34 or confirm with your CA before relying on it for discounts that were not pre-agreed.

A worked example: Surat textile trader and a partial return

Ambika Textiles in Surat sells 4,000 metres of viscose fabric to Meera Fashions, a registered garment maker in Surat, on 10 July 2026.

On 28 July Meera Fashions finds that 600 metres have a printing defect and returns them. Ambika Textiles issues credit note CN/26-27/0019 dated 28 July 2026 referencing AT/26-27/0455:

In its GSTR-1 for July, Ambika reports the invoice in Table 4 and the credit note in Table 9B, so its net output tax for that sale falls from ₹17,000 to ₹14,450. Meera Fashions sees the credit note in its August GSTR-2B, accepts it on IMS, and reverses ₹2,550 of ITC. On the customer ledger, Meera's outstanding drops from ₹3,57,000 to ₹3,03,450.

Suppose in September Ambika and Meera also agree a ₹5 per metre price increase on the remaining 3,400 metres because of a raw material surcharge that was in the contract. Ambika issues debit note DN/26-27/0004 for 3,400 × ₹5 = ₹17,000 plus CGST ₹425 and SGST ₹425, total ₹17,850, reported in Table 9B of the September GSTR-1. Meera claims the extra ₹850 as ITC once it appears in GSTR-2B. Fabric rates should be confirmed against the current schedule after the September 2025 rationalisation.

Debit notes on the purchase side

When you are the buyer, you will hear "debit note" used in a different sense. Your accounts team raises a debit note to a supplier to say: we are debiting your account by this amount because of short supply, damaged goods, a rate difference or a return. This is a commercial debit note. It is useful for your ledger and as evidence, but it does nothing under GST on its own.

The GST adjustment happens only when the supplier responds by issuing a GST credit note under Section 34, reporting it in their GSTR-1. Then it appears in your GSTR-2B and you reverse the ITC. So the purchase-side sequence is:

1. You record the issue against the purchase bill and send the supplier your debit note (or a simple email) with the invoice number, quantity and amount.
2. The supplier issues a credit note referencing their invoice.
3. You match the credit note to your debit note, reduce the payable in the vendor ledger, and reverse the ITC in the month it appears in GSTR-2B.
4. If the supplier never issues a credit note, you still owe the full GST-inclusive amount on paper, so chase it before the 30 November cut-off.

Keep in mind the 180-day rule as well: if you do not pay the supplier within 180 days of the invoice, ITC has to be reversed under the second proviso to Section 16(2). A pending dispute does not pause that clock, so settle the undisputed part.

Common mistakes

1. Cancelling the invoice instead of issuing a credit note when the goods have already been delivered or the invoice already reported.
2. Issuing a credit note for a bad debt. Non-payment is not a Section 34 ground; the tax stays payable even if the customer never pays.
3. Missing the 30 November deadline for last year's returns and discounts, losing the GST reduction permanently.
4. Using the same series for credit notes and invoices. Each needs its own consecutive series, as covered in invoice numbering rules.
5. Not referencing the original invoice on the note, or referencing the wrong one, which breaks the buyer's matching.
6. Treating a buyer's commercial debit note as a GST document and reducing output tax without issuing your own credit note.
7. Forgetting the ITC reversal as a buyer, which shows up as a mismatch between your GSTR-2B and GSTR-3B.
8. Issuing a "financial" credit note with GST shown on it. If the note does not qualify under Section 34 (for example a post-sale discount that was not pre-agreed), leave the tax columns blank.

How VyaparKit helps

The credit note and debit note tools in VyaparKit reference the original invoice, carry the Rule 53 fields, and run in their own financial-year series separate from the GST invoice series. Credit notes adjust the customer's balance in the customer ledger and outstanding statement, and purchase-side adjustments are recorded against the purchase bill, so the ITC table in the GST report reflects them. VyaparKit does not file GSTR-1 or act on the Invoice Management System; use its GSTR-1-ordered report as the source when you file.

Next steps

• List every invoice from FY 2025-26 that still needs a return or discount adjustment and issue the credit notes before the September GSTR-1, well ahead of 30 November.
• Set up separate CN and DN series for FY 2026-27 if you have not already.
• Ask registered buyers to confirm they have accepted your credit notes on IMS before you file.
• Review your GSTR-2B each month for credit notes from suppliers and reverse the matching ITC.
• Put your discount terms in writing at the start of each year so post-sale discounts qualify under Section 15(3)(b).