貿易成本與國際商品課稅原則的選擇──垂直產品差異的角色

TRADE COSTS AND THE CHOICE OF INTERNATIONAL COMMODITY TAX PRINCIPLE: THE ROLE OF VERTICAL PRODUCT DIFFERENTIATION

本文在Haufler et al.（2005）的模型基礎上，建構一個垂直產品差異化的兩國產業內貿易模型，探討產品品質差異程度與貿易成本如何影響國際商品課稅原則的選擇。本文為非對稱模型，以全球總福利水準高低來選擇商品課稅原則。本文發現，當產品品質差異大時，採取生產地原則的全球總福利大於消費地原則。隨著產品品質差異縮小時，當貿易成本較低時，採取生產地原則的全球總福利大於消費地原則；當貿易成本較高時，採取消費地原則的全球總福利大於生產地原則。此外，當產品品質差異更小時，採取消費地原則的全球總福利大於生產地原則。本文的另一貢獻是，將福利效果拆解成效率效果與貿易差額效果，用以分析這兩項效果如何影響不同課稅原則下高、低品質國家的福利效果。

Based on the model of Haufler et al. (2005), this paper constructs a vertical intraindustry trade model with two countries to explore how the degree of quality differentiation and trade cost affect the choice of commodity tax principles. This paper analyzes the choice of commodity tax base by world welfare in an asymmetric model. It is found that the origin tax principle is superior to the destination tax principle in terms of world welfare for the case of large differences in product quality. As the degree of quality differentiation shrinks, world welfare is higher under the origin tax principle when the trade cost is low; world welfare is higher under the destination tax principle when the trade cost is high. In addition, when product quality differences are smaller, world welfare is higher under the destination tax principle. Furthermore, this paper decomposes welfare effects into the efficiency effect and the trade balance effect, and investigates how the above two effects affect the welfare effect of high-quality and low-quality countries under two tax principles.