Levy of State GST on intra State supplies establishes supplier and reverse charge liability, including electronic commerce operator obligations. Imposes a State GST on intra State supplies (excluding alcoholic liquor for human consumption) at government notified rates and value determined under section 15, with deferred commencement for specified petroleum and fuel supplies; establishes reverse charge liability for notified categories, supplies from unregistered suppliers to registered recipients, and for services supplied through electronic commerce operators, with local representative or appointee liable where the operator lacks presence in the taxable territory.