The chapter analyzes the economic and environmental effects of environmental tax reforms in the four East Asian economies, focusing on the double dividend, using the E3ME-Asia model. The E3ME-Asia model that applied is global in nature, but the analysis is carried out at the national level. Despite there being a wide range of published papers on this topic in Europe or North America, in East Asia very few papers are found, and those mostly use CGE models. In today's context, where global harmonization seems difficult, the results of this model analysis seeking the East Asian harmonization could have substantial implication in the discussion of climate policy. The differences regarding positive double dividends are remarkable compared to other publications, especially when considering studies that have used CGE models. The possibility of a positive double dividend is created by revenue recycling, especially through a VAT reduction in these four East Asian countries.