Raw Ginger commission agents

dear experts, my query is Mr. A is agriculturist. Mr. B.(commission agent) purchase raw Ginger using the self purchase bill different parties in Karnataka. The total value of Ginger Rs 10 laks lakh. at the same day Mr. B sold the Ginger Mr. C by using his sale bill of Rupees value of Rs. 10 laks. Mr. B received amount his account including commission from Mr. C of Rupees Ten lakhs Twenty five Thousand. around yearly Transactions approximately may me 5 to 6 crore. Mr.B receive only commission. How is to be invoiceing in gst. how is to be treat in income tax for IT filing. pls suggest me.