What is the time limit for issuing a GST credit note for a sale made earlier?

Under Section 34(2) of the CGST Act, a credit note for a supply can be declared in the return for the month in which it is issued, but not later than 30 November following the end of the financial year in which the supply was made, or the date of filing the relevant annual return (GSTR-9), whichever is earlier.

If the credit note is issued after that cut-off, the supplier cannot reduce their output tax liability for it. Since the position depends on the facts of each case, confirm the specifics with your CA or tax advisor.