Pure agent principle excludes reimbursed third party costs from taxable supply value when separately invoiced and authorized by recipient. The value of supply under GST excludes expenditures a supplier incurs as a pure agent of the recipient where the supplier pays third parties on recipient authorization, separately indicates such payments on the invoice, and procures those supplies in addition to services supplied on the supplier's own account; a pure agent is contractually appointed, does not take title or use the procured goods or services for its own benefit, and receives only the actual amounts incurred in addition to its own charges.