Delhi VAT Registration is required for persons involved in the trading of goods in the State of Delhi. Delhi VAT Registration is mandatory for dealers whose turnover exceeds Rs.20,00,000 in a financial year.
However, a person may voluntarily apply for VAT registration even if his/her turnover does not exceeds Rs.20,00,000. Also If you wish to start your online business as merchant / seller & want to list your products on E-Commerce websites like Flipkart, Snapdeal etc then you must have TIN No. (TIN/VAT/CST are same thing).
CST Registration is mandatory if you are trading of goods inter states.