Global markets, national tax systems, and domestic politics: Rebalancing efficiency and equity in open states' income taxation

Competitive pressure on some capital income tax rates reinforces a generic quadrilemma or a four-way tradeoff in domestic income taxation. To maintain competitiveness, governments have to cut some tax rates on capital income down to international standards. If these cuts lead to a de-alignment of different rates on capital income, domestic allocation becomes more inefficient, all else being equal. Cutting all tax rates on capital income to a uniform low level, while maintaining high and progressive tax rates on labor incomes, avoids this inefficiency, but sacrifices comprehensive income taxation, that is, joint and equal taxation of capital and labor incomes. Finally, reducing all income tax rates to international standards, including top rates on labor income, implies a strong significant reduction in the progressiveness of labor income taxation (and/or significant revenue losses). As a result, governments that aim at all four goals - competitiveness, allocative efficiency, horizontal equity (comprehensive income taxation) and progressivity - and want to maintain a given revenue level cannot avoid seriously compromising one of them. This paper analyzes how this income tax quadrilemma has played out in seven OECD countries: Australia, Denmark, Finland, Germany, New Zealand, Norway, and Sweden. Combining the results of this matched comparison with exploratory data analysis for all OECD countries, the paper discusses the general implications of the quadrilemma for the domestic political economy of tax competition and the future of domestic compensation in open states.