Vat- query

Dear All, Pls help me the following issues:- A company registered in Kerala has branch in gujrat. If Gujrat branch purchased locally after paying VAT in Gujrat suppose to sell in kerala customers. Here there is no stock transfer as Gujrat branch will sell goods kerala customer directly. Pls let me know whether we need collect CST for the sale to kerala. As it leads to huge tax payment like Gujrat VAT, CST while selling to kerala and finally local VAT in kerala has to be paid by kerala customer. Thanks &Regards Shabeer