After reading complete information in kotak securities website.
It is not at all "FLAT". Read below
------------From Website--------------
Kotak Flat
Rs. 9 per trade Rs. 20 per trade
Monthly Fees Rs. 499 Nil
Max exposure against margin Rs. 9 Lakh Rs. 9 Lakh
Delivery Rs. 9 Rs. 20
Cash Square up Rs. 9 Rs. 20
Derivative Rs. 9 Rs. 20
The Flat brokerage rate is applicable for multiples of the order values mentioned below
Transaction Type Order Value
Delivery Rs. 5,000/-
Cash Square up Rs. 50,000
Derivative Rs. 50,000
For Example. If you place and intraday order of Rs. 100000 under the Kotak Flat Rs. 9 per trade plan then you would be charged Rs. 18 as brokerage.
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How come this is flat? if you are paying 9 Rs or 20 Rs for multiple of 5000 Rs trade value for delivery based.
If it is 9Rs, then you need to pay 499 Rs monthly fee.
We can't expect innovative products from consevative brokerage house.