Is sales interstate or intrastate

Hi,

There are 3 parties namely X in Gujarat & Y in Maharashtra & Z also in Maharashtra.X sold goods to Y.The tax invoice contained CST @ 2%.While the goods were in transit Y sold it to Z.The tax invoice raised by X on Y contained the name of Z as consignee.Y obtained E 1 form from X & raised a tax invoice on Z not charging any CST stating its exempt from tax subject to obtaining C form from Z. Will the sale by Y to Z be considered an interstate or intrastate sale?Will Y be able to claim exemption u/s 6(2) or will the sales be considered to be intrastate as both Y & Z are in Maharashtra irrespective of whether the goods is sold by Y to Z in transit & he will have to charge VAT on Z?

Please friends reply soon.