Issuing a Credit Note for a GST-Compliant Refund

When an issued invoice needs to be worth less — an overcharge, a return, a discount — a credit note is the compliant way to record it, referencing the original invoice rather than touching it directly. See credit note vs debit note for when this is the right document versus a debit note.

What a compliant credit note contains

• Its own unique number, in its own sequence.
• A clear reference to the original invoice number and date.
• The value being reduced, and the corresponding GST reduction, calculated proportionally.
• The reason for the reduction.

The deadline that actually matters

A credit note can technically be issued at any time — but for it to actually reduce your GST liability, its details must be declared in a return by 30 November following the end of the financial year the original supply belongs to, or the date you file that year's GSTR-9 annual return, whichever comes first. Miss that window, and the credit note can still exist as a record between you and your customer, but it no longer reduces what you owe the government for that supply.

For a supply made in FY 2025-26, for example, a credit note needs to be declared by 30 November 2026 (or the earlier annual return date) to have GST effect — not an unlimited window, even though nothing stops you physically issuing the document later.

What the customer needs to do

If your customer already claimed input tax credit on the original invoice, they need to reverse the proportional ITC once the credit note is issued — the reduction flows through to their side too, not just yours.

This deadline is a genuine detail worth having a reminder for — a credit note that's correct in every other way but declared too late quietly stops doing what it was meant to do. The underlying provision is Section 34 of the CGST Act.