This paper studies the effect of an emission tax on the relocation decision in a duopoly with vertical product differentiation. We establish the relationship between an exogenous product quality markup, relocation cost, and emission taxation in a two-country-setting for three cases: (a) an environmental tax set only by one country, (b) non-cooperative environmental taxation in both countries, and (c) coordinated environmental taxation. We show that a larger product quality markup and, thus, weaker competition can serve as a substitute for environmental policy as both reduce emissions. However, weaker competition makes firm relocation more likely, which results in emission shifting instead of emission reduction. The higher the product quality markup, the more likely it is that at least one firm relocates to the foreign country. Emission taxation in the foreign country changes location decisions: If also the foreign country applies an emission tax, at least one firm stays in the home country. If both governments set taxes non-cooperatively, the low-quality firm always stays in the home country. If both countries set taxes cooperatively, both firms are more likely to stay in the home country. However, relocation of the low-quality firm is a possible outcome under cooperative taxation.

本文研究了在具有垂直产品差异的双头垄断企业中，排放税对重新安置决策的影响。我们在两种情况下针对两个国家建立了外源产品质量标记，搬迁成本和排放税之间的关系：（a）仅由一个国家/地区设定的环境税，（b）两种国家/地区均不合作进行的环境税国家，以及（c）协调环境税。我们表明，更大的产品质量加价，以及因此更弱的竞争可以替代环境政策，因为它们都减少了排放。但是，竞争越弱，企业搬迁的可能性就越大，这将导致排放转移而不是减少排放。产品质量标记越高，至少一家公司搬到国外的可能性就越大。外国的排放税会改变地点决定：如果外国也要征收排放税，则至少有一家公司留在本国。如果两国政府非合作地设定税收，那么低质量的公司将始终留在本国。如果两个国家合作设定税收，则两个公司都更有可能留在本国。但是，根据合作税收，低质量公司的搬迁是可能的结果。