A carbon tax would need to interact with existing state and regional greenhouse gas programs, renewable subsidies, programs for state renewable portfolio standards, and other subnational policies.
A carbon tax will interact with other policies that are intended to reduce carbon dioxide emissions and encourage clean sources of energy and energy efficiency. This paper examines these policy interactions. A well-designed carbon tax can be an efficient instrument for reducing emissions, yet whether it will be implemented in an efficient manner is uncertain. A legislatively determined tax may not fully reflect up-to-date scientific and economic information. Behavioral and institutional factors suggest that a tax may not have its fully intended effect. These considerations suggest that climate policy should and will continue to be a complex mix of regulaions at various levels of government, even with a carbon price. Nonetheless, the possibility of unintended interactions among policies remains. The role for policies to encourage renewables and energy efficiency depends on the stringency of the carbon tax and presence of externalities related to technological learning and the energy efficiency gap.