Applicability of GST and tax audit

One of my client is distributor of gift cards. This card contain a value of Rs. 10000/- which can be use the end consumer like debit card. Company supply it to distributor at a discount @ 1.2% and issue bill of supply.  For e.g. 10cards x 10000= 100000-1200= 98800. and Zero GST. distributor further supply it to businessman at a discount  0.5% and issue bill of supply. For E.g. 10cards x 10000= 100000-500= 99500. and Zero GST. You are requested to  provide the following clarification

1. Is there any GST liability arise on distributor in this transaction. GST on Discount 1.2%-0.5%

2. How to compute Turnover of distributor for TAX audit purpose. Turnover would be consider 99500 or Net discount amount.

Thanks in advance