turnover discount

Issuance of credit note with GST is not mandatory..

If supplier wishes to adjust GST liability to the extent of discount - should issue credit note with GST and recipient need to reverse credit.

If supplier do not want to adjust GST liability - credit note can be issued without GST (financial credit note as per said circular)

Link - https://www.cbic.gov.in/resources//htdocs-cbec/gst/circular-cgst-2.pdf;jsessionid=FCA5136F6050D742FC377CDAD5D7EFF7