Taxable value = transaction value of supply, which includes all costs charged by the supplier but excludes discounts given in the invoice (if discount was agreed before supply and mentioned in invoice).
Pre-supply discounts mentioned on the invoice are deductible. Post-supply discounts can be deducted only if the recipient reverses the corresponding ITC.
If freight is charged separately by the supplier and appears on the same invoice, it is included in taxable value. If the buyer arranges their own freight, it's excluded.
Packing charges charged by the supplier are included in taxable value.
