Scale Economies in Cross-Border Shopping and Commodity Taxation

A simple inventory theoretic model of cross-border shopping with transaction and storage costs is developed. Consumers incur fixed transaction and transportation costs to access the foreign market in which a perfect substitute of the domestic good is available. We show that the size of the optimal tax is inversely related to the size of domestic transactions. This result provides a simple example of a more general principle, that is, when there are increasing returns to scale in tax avoidance with respect to the quantities involved, then smaller transactions should be taxed more heavily than larger transactions. This revised version was published online in July 2006 with corrections to the Cover Date.