This paper introduces the Tax Complexity Index (TCI). The TCI comprehensively measures the complexity of countries’ corporate income tax systems faced by multinational corporations. It builds on surveys of highly experienced tax consultants of the largest international tax services networks. The TCI is composed of a tax code subindex covering tax regulations and a tax framework subindex covering tax processes and features. For a sample of 100 countries, we find that tax complexity varies considerably across countries, and tax code and framework complexity also vary within countries. Among others, tax complexity is strongly driven by the complexity of transfer pricing regulations in the tax code and tax audits in the tax framework. When analyzing the associations with other country characteristics, we identify different patterns. For example, we find a positive association of GDP with tax code complexity and a negative association with tax framework complexity, suggesting that highly economically developed countries tend to have more complex tax codes and less complex frameworks. Overall, the tax complexity measures can serve as valuable proxies in future research and supportive tools for a variety of firm decisions and national and international tax policy discussions.

本文介绍了税收复杂性指数（TCI）。TCI综合衡量跨国公司面临的各国企业所得税制度的复杂性。它建立在对最大的国际税务服务网络经验丰富的税务顾问的调查基础上。TCI 由涵盖税收法规的税法子索引和涵盖税收流程和特征的税收框架子索引组成。对于 100 个国家/地区的样本，我们发现各个国家/地区的税务复杂性差异很大，各个国家/地区的税法和框架复杂性也各不相同。其中，税务复杂性很大程度上是由税法中转让定价法规和税务框架中税务审计的复杂性驱动的。在分析与其他国家特征的关联时，我们发现了不同的模式。例如，我们发现GDP与税法复杂性呈正相关，与税收框架复杂性呈负相关，这表明经济高度发达国家往往拥有更复杂的税法和不太复杂的框架。总体而言，税收复杂性衡量标准可以作为未来研究的宝贵代表，以及各种企业决策以及国家和国际税收政策讨论的支持工具。