Commercial sample import rules: duty relief subject to unit and annual value limits, re export undertakings and Customs oversight. Importation of commercial samples is permitted duty free when goods are bona fide samples supplied free of charge and comply with exclusions; duty relief is conditional on per unit and annual aggregate value and quantity limits, special rules apply to engineering prototypes (including rendering them unsaleable or furnishing security and undertaking to re export), freight and insurance treatment varies with value, and non compliance exposes importers to investigation, penalties and prosecution.