Key takeaways
What this article covers, in order:
- Note or amendment: which one do I need?
- What does a valid credit note need?
- Is there a deadline for credit notes?
- Where do notes go in GSTR-1?
- How does IMS change things for credit notes?
- How do amendments work?
A customer calls: half the shipment of tiles arrived cracked, and they're sending ₹48,000 worth back. Do you issue a credit note? Amend the invoice? Both? Here's the rule of thumb. If the transaction changed after the invoice (returns, discounts, price revisions), issue a credit note to reduce it or a debit note to increase it. If the invoice was reported wrongly in your GSTR-1 (wrong GSTIN, typo in the value, wrong place of supply), amend it. Credit and debit notes are reported in GSTR-1 and flow into GSTR-3B; amendments go in Tables 9A, 9C, 10 or 11, or through GSTR-1A if you catch it before filing GSTR-3B for the period.
Mixing those two up is behind a surprising number of mismatch notices. So let's separate them properly.
Note or amendment: which one do I need?
| What happened | Fix | Why |
|---|---|---|
| Goods returned | Credit note | The supply itself shrank |
| Post-sale discount agreed in the contract | Credit note | Taxable value went down |
| Rate charged was too high | Credit note | Tax charged was more than due |
| Rate charged was too low, or price increased | Debit note | Taxable value or tax went up |
| Buyer's GSTIN typed wrong in GSTR-1 | Amendment | The invoice was fine; the reporting was wrong |
| Invoice value keyed wrongly in GSTR-1 | Amendment | Same |
| Wrong place of supply in GSTR-1 | Amendment (plus tax correction if IGST vs CGST/SGST changed) | Reporting error with a tax effect |
| A whole invoice was left out of GSTR-1 | Report it in the next GSTR-1 (or GSTR-1A for the same period) | It's an omission, not an amendment |
A quick test. Would the paper invoice you handed the customer still be correct? If yes, and only the return is wrong, amend. If the paper invoice no longer reflects the deal, issue a note.
What does a valid credit note need?
Much the same as an invoice: your name, address and GSTIN, a serial number, date, the buyer's details and GSTIN if registered, the original invoice number and date it relates to, taxable value, rate and tax amount being reduced, and a signature. One credit note can cover several invoices, but you have to be able to show which ones.
Debit notes work the same way, in the other direction.
Is there a deadline for credit notes?
Yes, and it's a hard one. Under Section 34, a credit note for supplies of a financial year has to be declared by the earlier of 30 Nov of the next financial year (30 Nov 2027 for FY 2026-27 sales) or the date you file the annual return.
So for a sale made in Feb 2026 (FY 2025-26), the credit note has to go into a return filed by 30 Nov 2026. Issue it in Dec 2026 and you can still give the customer a commercial discount, but you can't reduce your GST liability with it.
Debit notes don't have the same cut-off for issuing. The buyer's ITC on a debit note follows the Section 16(4) deadline, counted from the financial year of the debit note.
Where do notes go in GSTR-1?
To a registered buyer: Table 9B, as CDNR. It reaches the buyer's IMS and GSTR-2B like an invoice.
To an unregistered buyer, where the original was a B2C Large or export invoice: Table 9B, as CDNUR.
To an unregistered buyer on a B2C Small sale: no separate entry. Net it into that month's Table 7 summary for the same place of supply and rate.
And in GSTR-3B, your liability in Table 3.1 is auto-populated net of the credit notes you reported. Since the liability tables are now locked to what comes from GSTR-1, you can't adjust them by hand in GSTR-3B. Get the notes into GSTR-1 (or GSTR-1A) and the net figure follows.
How does IMS change things for credit notes?
Quite a lot, actually. Your buyer now sees your credit note in their Invoice Management System and can accept it, reject it, or (for a limited time) keep it pending.
If they accept, they reverse the ITC on their side and your liability reduction stands. If they reject it, the reduction doesn't simply go through; the portal adjusts on your side, and you should expect your liability to come back. Pending can only be held for one tax period on credit notes before it's treated as accepted. Buyers can also add remarks, and when they declare a partial or no ITC reversal against your note, a remark is required.
So the practical advice: tell your customer before you report a credit note. "We're issuing CN/26-27/018 for ₹48,000 against INV/26-27/0912, please accept it in IMS." It saves a month of back-and-forth. If anything about this flow is unclear for your situation, the GST portal's IMS advisories are the place to confirm.
How do amendments work?
You amend through the amendment tables in a later GSTR-1:
- Table 9A for B2B, B2CL and export invoices
- Table 9C for amending credit and debit notes already reported
- Table 10 for B2CS summaries
- Table 11 for advances
You pick the original invoice, and change what was wrong. The buyer sees the amended version in their GSTR-2B.
There's a time limit here too. Amendments for a financial year can be made until 30 Nov of the next year (30 Nov 2026 for FY 2025-26) or the annual return filing, whichever comes first.
When GSTR-1A is better
If you spot the error after filing GSTR-1 but before filing GSTR-3B for that same period, use GSTR-1A. It lets you add or fix records for the current period so your GSTR-3B liability is right from the start. It can be filed only once per period, so finish your whole review first. After GSTR-3B is filed, you're back to the amendment tables in a later GSTR-1.
Three short scenarios
Returned tiles. Prakash in Morbi sold ₹2,40,000 of tiles to a registered dealer in Indore on 4 Sep 2026. On 18 Sep 2026, ₹48,000 worth come back. He issues a credit note for ₹48,000 plus IGST, reports it in the Sep 2026 GSTR-1 as CDNR, and phones the dealer to accept it in IMS.
Wrong GSTIN. Fatima's catering firm in Hyderabad reported an Aug 2026 invoice with one digit wrong in the client's GSTIN. She files GSTR-1 on 11 Sep 2026 and notices on 15 Sep 2026, before her GSTR-3B. She uses GSTR-1A to fix it. If she'd caught it in Oct 2026, she'd amend through Table 9A of a later GSTR-1.
Price escalation. A steel trader's contract allows a rate revision after the invoice. The customer agrees to pay ₹12,000 more. That's a debit note, reported in Table 9B, and the extra tax is paid with that month's return.
Checklist before you report a note or amendment
- [ ] Decided: transaction changed (note) or reporting error (amendment)?
- [ ] Credit note links to the original invoice number and date
- [ ] Within the deadline for that financial year (30 Nov 2026 for FY 2025-26)
- [ ] Registered buyer: reported as CDNR and buyer informed about IMS
- [ ] B2C Small: netted into Table 7
- [ ] Same-period error and GSTR-3B not filed yet: use GSTR-1A
- [ ] Older error: amendment table in the next GSTR-1
Disputed credit notes, large volume rebates, or anything near the 30 Nov 2026 cut-off for FY 2025-26 are worth running past your CA.
How HelloBooks helps
In HelloBooks a credit or debit note is created against the original invoice, so the link is there for your GSTR-1. Notes to registered buyers land in the right section, and B2C reductions are netted into the summary. You then file GSTR-1 and GSTR-3B directly to the GST portal from inside HelloBooks on the Free plan for one GSTIN. Have a look at GSTR returns and the GSTR-1 filing page.
FAQs
Can I issue a credit note without GST?
Yes, as a financial or commercial credit note. It settles the money but doesn't reduce your GST liability, and it isn't reported in GSTR-1.
Can one credit note cover several invoices?
Yes, as long as it clearly references each invoice it relates to.
My customer rejected my credit note in IMS. What now?
Talk to them first. If the rejection was a mistake, you'll need to sort it out with them; if they genuinely disagree, the reduction won't stand and your liability will reflect that. Check the GST portal's IMS guidance for how the adjustment shows up.
Can I amend an invoice from FY 2024-25 now?
Generally no. The amendment window for FY 2024-25 closed on 30 Nov 2025 or on your annual return date, whichever was earlier.
Do debit notes affect my buyer's ITC?
Yes. They show up in the buyer's GSTR-2B and the buyer can claim ITC on the extra tax.
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