HSN classification and GST rates determine tax treatment for goods, with headings and form dictating applicable rates. Classification of goods by HSN headings determines the applicable GST rate, with specific mappings of commodities to headings and rates. The guidance distinguishes rates by product form or composition (for example fresh v. dried produce, constituent fibres, or sub headings with different rates), notes residual entries for unspecified items, and records special treatments including nil or concessional rates for certain agricultural inputs, reverse charge for supplies by agriculturists, and a compensation cess on imported coal. Retail sale price rules and transaction value clarify rate application.