The cap rate could be higher, or it could start higher and be gradually tightened, or it could vary with an individual’s income level. But the economic and political attractiveness of a cap consists in its ability to raise substantial revenue without eliminating specific tax expenditures.
这一政策如何设计，选择很多。上限率可以定得高一些，也可以起点上限率较高而逐渐收紧，也可以随个人收入水平而定。但上限政策的经济和政治吸引力在于它能够大幅增加收入而不必取消具体的税收开支项目。