Under GST, there's generally no strict time limit for issuing a debit note. However, for credit notes, the deadline is typically the due date of the September return of the following financial year. There are proposals to extend this deadline to 30th November.
05 February 2022
For debit note - no time limit. For credit note till date - upto due date of September return of following FY and proposed to be increased till 30th November. (Dates of showing in return)