GST computation on Commission received in Forex

SKumar (Manager) (385 Points)

30 November 2019  

Please guide me on how to compute GST on Commission received from Foreign Principal. 

Gross receipts =100USD

Is

a)  GST to be charged on 100 USD  ( then commission @ 18% = USD 18)

or

b)  100 USD treated as inclusive of GST? (then commission @ 18% = USD 15.25)