1. The concept of C form is very simple. When Goods are moving from one state to another state, CST comes into play. Generally Goods move from one state to another state, generally they are either of Resale and/or for use in manufacturing of Goods.
2. When such goods are purchased either for resale and /or for use in manufacture, State Government collects the tax when goods are resold or when manufacturing goods are ultimetaly sold. Thus Govt gets that tax on final selling price.
3. In such case when goods are moved from one state to another if full tax is paid by purchaser to Seller, then there will price rise, as purchaser is not entitled for SETOFF of CST paid on purchases.
4. To avoid this double taxation C Form plays importnat part. When one Registered Delar purchase goods from another registered Dealer, they can use C form , and then selling dealer will charge CST at reduced rate ( Section 8(2) of CST ACt
There is lot more things about C form, but i think u are interested in general principles.
so thats enough for the pen