Business rarely goes exactly as the original invoice says — goods get returned, prices get revised, quantities get corrected. GST handles these adjustments through two documents: the credit note and the debit note. Both are always issued by the supplier, and both are governed by Section 34 of the CGST Act.
Credit note vs debit note — the simple rule
- Credit note → issued when the original invoice value or tax was too high (reduce it).
- Debit note → issued when the original invoice value or tax was too low (increase it).
A useful way to remember it: the note corrects the invoice in favour of whoever was disadvantaged, but it is always the supplier who issues it, referencing the original tax invoice.
When to issue a credit note
A supplier issues a credit note when:
- Goods are returned by the customer
- The supply was deficient (quality issues, short supply)
- The price is revised downward after the invoice
- A discount agreed at or before supply is given post-sale (subject to conditions)
- Tax was charged at a higher rate than applicable
The credit note reduces the supplier’s output tax liability — but only if the corresponding reduction in tax is passed on and the recipient reverses any ITC already claimed.
When to issue a debit note
A supplier issues a debit note when:
- The invoice undervalued the supply
- Additional goods/services were supplied against the same invoice
- The price is revised upward
- Tax was charged at a lower rate than applicable
A debit note increases the output tax liability.
The time limit on credit notes
This is the detail most people miss. A credit note that reduces tax liability must be declared in a return by the earlier of:
- 30 November following the end of the financial year in which the original supply was made, or
- the date of filing the annual return for that year.
Miss this window and you cannot reduce your tax liability through the credit note. A debit note has no such time limit — it can be issued whenever an upward correction is needed.
What a credit/debit note must contain
As per Rule 53, the document should include:
- The words “Credit Note” or “Debit Note” clearly
- Supplier’s name, address and GSTIN
- A unique serial number for the financial year
- Date of issue
- Recipient’s name, address and GSTIN (if registered)
- Reference to the original tax invoice (number and date)
- The taxable value, rate and amount of tax being credited or debited
- Signature of the supplier
How they are reported in GSTR-1
Credit and debit notes flow into GSTR-1:
- CDNR — notes issued to registered persons (linked to the original B2B invoice)
- CDNUR — notes issued to unregistered persons
The system then adjusts your output tax: credit notes reduce it, debit notes increase it, in the period they are declared.
A quick example
You sold goods for ₹1,00,000 + ₹18,000 GST. The customer returns a quarter of the goods:
- Credit note taxable value: ₹25,000
- GST on credit note @ 18%: ₹4,500
- Your output tax reduces by ₹4,500 (provided the buyer reverses the matching ITC)
- Reference the original invoice number on the credit note
The bottom line
Use a credit note to reduce an over-stated invoice (returns, discounts, downward revisions) and a debit note to increase an under-stated one — always issued by the supplier, always linked to the original invoice, and always reported in CDNR/CDNUR. Watch the 30 November deadline for credit notes that reduce your tax.
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