Value of supply excludes Kerala Flood Cess for GST valuation, with the cess separately collectible and subject to GST compliance. Rule 32A deems the value of supply for goods or services on which Kerala Flood Cess is levied to be the value determined under the Act's valuation provisions but excludes the cess from that value; the cess is separately collectible by showing it on invoices, and all GST procedural and compliance provisions apply to its levy, collection and delayed payment interest.