Customs transaction value principle requires declared import/export prices to govern duty assessment, subject to valuation factors and review. Transaction value is the primary basis for Customs valuation under Section 14 and the Customs Valuation Rules, 2007: the price actually paid or payable is to be adjusted by specified valuation factors (additions such as commissions, packing, royalties, transport and insurance; and allowable deductions) and accepted only if valuation conditions and documentary verification are satisfied. If the transaction value cannot be accepted or is doubtful, valuation follows a hierarchical sequence of methods-identical goods, similar goods, deductive, computed, and fallback methods-and the declared value may be rejected under Rule 12.