We generated the sales invoice in October 2025 without including the customer’s GST number and reported it as a B2C invoice in GSTR-1, with GST charged.
Now, in October 2026, (After one Year) the customer is requesting us to add their GST number and share the revised invoice.
Could you please confirm whether it is possible to revise the invoice at this stage?
10 October 2026
Yes, it is possible to amend the October 2025 invoice to add the customer's GSTIN. Because the current date is October 2026, you are still within the statutory deadline under Section 37(3) of the CGST Act (which is 30th November 2026 for FY 2025–26). You should amend the entry from B2C to B2B in your upcoming GSTR-1 return immediately so the recipient can claim the ITC.