Gst on sale

Sir

Our Factory is at West Bengal. I am citing three cases . Kindly advice me .

Case  1. One Customer is having his Head office in Maharashtra.We receive order from Mumbai (.e bill to Party is at Mumbai) His one of the factory is at  West Bengal.(i.e. Shipt to Party is at West Bengal) If we supply goods at his west bengal factory then which category of GST is applicable. (i.e CGST/SGST/IGST)?

Case 2. The above customer is having another factory  at Goa. If we supply goods at his Goa factory then which category of GST is applicable. (i.e CGST/SGST/IGST).?

Case3.Another customer is having is head office at West Bengal (i.e. Bill to party is at West Bengal) His factory at Gujrat (i.e. ship to party is at Gujrat ) If we supply goods at his Gujrat Factory then which category of GST is applicable. (i.e CGST/SGST/IGST).?