GST rate on credit notes post rate change

[BIJO SCARIA]

I sold goods before the GST rate change (say, on 20th September 2025, when the applicable tax rate was 28%). The customer returned the goods after the rate change (say, in October 2025, when the tax rate became 18%). While issuing a credit note in October 2025, should I apply the old tax rate of 28% or the new rate of 18%?

AI Summary

Credit notes for returned goods should match GST rate charged on the original invoice and adjust taxes in issue period If goods were supplied when a higher GST rate applied, a credit note for their return should generally reflect the tax treatment of the original supply, i.e., the rate charged on the original invoice. The supplier should reduce output tax and the recipient adjust input tax credit based on that original rate; procedural timing and returns should follow GST rules for issuing credit notes and for adjusting tax in the period the credit note is issued. Discrepancies or transitional rules at the time of a rate change may require checking applicable notifications or guidance.