Forgot to upload Credit note issued

Credit notes do not have to match the same GSTR-1 period as the original invoice. You can upload a credit note issued in an earlier month in any subsequent GSTR-1, as long as you stay within the time limit.

The deadline for FY 2025-26 credit notes is November 30, 2026 (or before GSTR-9 filing, whichever comes first). So you can include the missed credit note in your September 2026 GSTR-1, due October 11.

Two things to keep in mind: (1) enter the original invoice date and number correctly in the credit note, and (2) your buyer GSTR-2B will show it only in the period when you upload it (not the original month), so let them know to reverse ITC from that period.

This [GST credit note guide](https://taxgarden.in/blog/gst-debit-note-credit-note-section-34-rules-india-2026) covers the Section 34 rules and time limits.