Composite supply principle treats a multi-component transaction as supply of the principal component, determining GST treatment and time of supply. A multi-component transaction is a composite supply where one component is the principal supply; under section 8(a) such composite supply shall be treated as a supply of that principal component, with the applicable GST rate and the rules on time of supply determined by whether the principal supply is goods or services, while ancillary items are treated as incidental to and taxed with the principal supply.