New amendments in tn vat

Hi,

There has been recent amendments in tamilnadu vat where in you need to generate E Transit pass for sending materials out side state particularly iron and steel.It is heard that vat input can not be availed against cst sales. That is if you buy materials from local dealer by paying 5% vat and sell outside state @ 2% against c form.You need to reverse 3% and pay back to the government.Can any one through light on this please ?