gst on discount.

Discounts like trade discount, quantity discount etc. are part of
the normal trade and commerce. Therefore, pre-supply discounts
i.e. discounts recorded in the invoice have been allowed to be
excluded while determining the taxable value.
Discounts provided after the supply can also be excluded while
determining the taxable value, provided two conditions are
met, namely - (a) discount is established in terms of a pre supply
agreement between the supplier & the recipient and such
discount is linked to relevant invoices and (b) input tax credit
attributable to the discounts is reversed by the recipient.