The potential impacts of a domestic offset component in a carbon tax on mitigation of national emissions

The current global momentum for carbon pricing has lately produced innovative hybrids: carbon taxes allowing the use of offsets from emission sources not targeted by the carbon tax for compliance with the tax load. This study aims at filling the knowledge gap in existing literature by exploring the potential impacts of domestic offset components in carbon taxes on mitigation of national emissions, including the country examples Colombia, Mexico and South Africa. The findings indicate that the use of offsets in carbon taxes may significantly influence mitigation of national emissions both positively and negatively. On the one hand, this model may result in real emission reductions from offset projects and positive spillover effects of efforts to reduce emissions from emission sources covered by the carbon tax to other emission sources. Furthermore, the offsetting component can be used as a bargaining chip in political negotiations facilitating the introduction of mitigation policies and measures and/or strengthening their ambition level. On the other hand, it also entails serious risks: Offsetting could compromise the environmental integrity of the carbon tax through low-quality offsets. Furthermore, offsets reduce incentives to curb emissions in the emission sources covered by the carbon tax, potentially leading to carbon lock-in effects. Moreover, an offsetting component could provoke opposition to further climate policies and measures for emission sources generating offsets, as replacing the offsetting component with mandatory emission reduction policies would eliminate revenues from offset credits. General opposition of stakeholder groups to the introduction of offsets may even hinder the introduction of carbon pricing instruments and offsetting altogether. The study identifies options that could be employed to increase potential positive effects of introducing an offset component to a carbon tax and mitigate related risks, pointing to the country examples included, where appropriate