Competitiveness concerns and possible leakage of tax impacts can be reduced if environmental taxes are introduced at similar levels in neighbouring countries. A platform focussing on cooperation related to environmental taxation could facilitate exchange of experiences and information between countries and support steps towards harmonization of specific environmental tax rates and environmental taxes most likely to result in cross-border smuggling, such as fuel taxes. These policy processes offer Governments the chance to collaborate on the development of carbon taxes and fossil fuel subsidy reform, agree timelines, and exchange and learn from each other's experiences.