In case of inter state transaction VAT will not apply. VAT is replacing the local sales tax of the state. So it will not have impact on inter state transaction but if VAT will be introduced then CST will be 2% instead of 4% on declaration filed by the purchaser so out put tax will be reduced. Another thhing no ITC will be available for amount of CST paid to the seller state as both state are diff ITC will not be vailable
You have mentioned that if VAT is introduced CST will be 2%. VAT is state act and CST is Central. VAT implementation in Chattisgarh is not going to bring down CST to 2% from 4%. Provisions of CST reduction has to be taken by Central Govt, and there are various factors political, industrial, compensation to state govt etc.