Optimal taxation and congestion externalities in a model of household time allocation

When wanting to solve the externality problem in the transport sector the tax system is an available instrument and the optimal tax system has been analyzed extensively. Unfortunately many of the approaches fail to take account of the insights pointed out in Becker (1965) that the allocation of household time is important for the characterization of household behavior. Since transports main characteristic is that it consumes time this insight should be applied to the transport sector. Recent papers have analyzed the optimal tax system in this setup (Kleven (2004), Nielsen and Pilegaard (2004)) in situations with and without atmospheric externalities. It was shown that the inclusion of household time changes the formulas for optimal taxation and these changes has direct policy implications. If the Becker setup is to be applied to the transport sector an analysis of the optimal tax system in the presence of congestion externalities is needed. This lack of insight is the focus of the present paper. The purpose here is to implement congestion type externalities in a Becker-like setup which explicitly models the use of household time. The paper demonstrates the strength of the Becker approach since existing tax results emerge as special cases in the present setup. The formulas derived for the optimal tax is a valuable guidance when designing the tax system in the transport sector.

在解决交通领域外部性问题时，税收体系是可行的政策工具，且最优税收体系已得到广泛研究。遗憾的是，多数相关研究未能纳入贝克尔（Becker, 1965）所提出的核心洞见：家庭时间配置对刻画家庭行为至关重要。鉴于交通的核心特征是消耗时间，该洞见理应应用于交通领域。近期已有文献在该分析框架下，针对存在与不存在大气外部性的场景展开了最优税收体系研究（克莱文[Kleven, 2004]、尼尔森与皮勒加德[Nielsen & Pilegaard, 2004]）。研究表明，纳入家庭时间变量会改变最优税收的计算公式，且该调整具备直接的政策含义。若要将贝克尔分析框架应用于交通领域，则需针对存在拥堵外部性的场景开展最优税收体系分析。现有研究的这一空白，正是本文的研究焦点。本文旨在在一个明确刻画家庭时间使用情况的类贝克尔分析框架中，引入拥堵型外部性。本文验证了贝克尔分析方法的优越性：既有税收研究结论均可作为本文框架下的特殊情形推导得出。本文推导的最优税收计算公式，可为交通领域的税收体系设计提供极具价值的参考依据。