Communications of the
Korean Mathematical Society CKMS

We define {\em progressive tax rate functions}, study their properties, and describe some smooth models. The key requirement, defining the progressive nature of the taxation model, is that the progressive tax rate functions should have infinite contact with the zero function at the origin, in order to care the poor. In constructing a wide array of such functions, {\em assisting functions} are introduced.

Keywords: progressive taxation, non-analytic smooth function, tithe, convexity

MSC numbers: Primary 91B64, 26A24