Credit note issued later for Addl Discount/ Scheme Discount or for Target Achievement

section 15 [3]
The value of the supply shall not include any discount which is given--

[a] before or at the time of the supply if such discount has been duly recorded in the invoice issued in respect of such supply; and

[b] after the supply has been effected, if-

[i] such discount is established in terms of an agreement entered into at or before the time of such supply and specifically linked to relevant invoices; and

[ii] input tax credit as is attributable to the discount on the basis of document issued by the supplier has been reversed by the recipient of the supply.

Thank you for the revert. Iv been thru the provision myself. I'm sceptical about credit notes issued without tax implications. The provision is silent.