Issue - Whether GST shall be charged after deduction of both Trade Discount and Cash Discount?
As per Section 15 of CGST Act, 2017, GST shall be charged on Net Value i.e. after discount (Trade Discount and Cash Discount).

It means GST shall be calculated on the Gross Price less Discounts allowed (both Trade Discount & Cash Discount).
Net Value = Gross Value - Trade Discount - Cash Discount
And GST Shall be Caluculated on Net Value.
Let's see one example to understand better.
Example 1 : Ram & Co. (Delhi) sold goods to Mohan & Co. (Delhi) of List Price Rs. 1,00,000, less Trade Discount 20%, Cash Discount is 2%. Mohan & Co. paid the amount at the time of Sale. Rate of CGST & SGST is 6% each. Invoice prepared by Ram & Co. shall be as follows:
List Price 1,00,000
Less: Trade Discount (20%) 20,000
80,000
Less: Cash Discount 1,600
78,400
Add: CGST @6% 4,704
Add: SGST @6% 4,704
87,808
Journal Entry for the above:
In the books of Ram & Co.
Cash A/c Dr. 87,808
Discount AllowedA/c Dr. 1,600
To Sales A/c 80,000
To Output CGST A/c 4,704
To Output SGST A/c 4,704
I hope now you have clearly understood the effect of Trade Discount and Cash Discount while calculating the value GST.
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