In 2003 Japan proposed a Climate Change Tax to reduce its CO2 emissions to the level required by the Kyoto Protocol. If implemented, the tax would be levied on fossil fuel use and the revenue distributed to several sectors of the economy to encourage the purchase of energy efficient equipment. Analysis using the MIT Emissions Prediction and Policy Analysis (EPPA) model shows that this policy is unlikely to bring Japan into compliance with its Kyoto target unless the subsidy encourages improvement in energy intensity well beyond Japan’s recent historical experience. Similar demand-management programs in the U.S., where there has been extensive experience, have not been nearly as effective as they would need to be to achieve energy efficiency goals of the proposal. The Climate Change Tax proposal also calls for restricting Japan’s participation in the international emission trading. We consider the economic implications of limits on emissions trading and find that they are substantial. Full utilization of international emission trading by Japan reduces the carbon price, welfare loss, and impact on its energy-intensive exports substantially. The welfare loss with full emissions trading is one-sixth that when Japan meets its target though domestic actions only, but Japan can achieve substantial savings even under cases where, for example, the full amount of the Russian allowance is not available in international markets.