90年代以来税制改革出现了新的特点 ,改变了单纯的减税政策 ,而是有增有减 ,世界各国的税收制度越来越呈现求同存异的特点。这些情况的出现不是偶然的 ,而是有着深刻的理论和经济背景。近十年来世界各国税制的实践为 2 1世纪的税制改革提供了许多可借鉴的经验。不断发展和变化的形势也为 2 1世纪的税制改革提出了一系列的难题 ,这些问题需要在 2 1世纪税制改革与优化过程中不断加以克服。 Since the 1990s, the reform of the tax system has brought about new characteristics, changed the simple tax reduction policy, but increased and decreased, and the taxation system of various countries in the world has been showing more and more characteristics of seeking common grounds while reserving differences. The emergence of these situations is not accidental, but has profound theoretical and economic background. The tax practice in various countries in the world over the past decade has provided many lessons for the tax reform in the 21st century. The continuous development and changes have also posed a series of problems for the tax reform in the 21st century. These problems need to be constantly overcome in the process of tax reform and optimization in the 21st century.