Cst or vat?

Hi All!

Please resolve this query. The Company is engaged in O&M and their site is in Maharashtra. They purchase some material from a vendor in Maharashtra to de delivered at the site in mhaarashtra. However, the Billing is in the name of the co, which is based in Chennai. My doubt is whether it's an interstate sales or Local sales? CST or VAT? Please substantiate with the relevant provisions.

Thanks in advance!