The equity of systems is judged by at least two criteria ability to pay and the benefits received principle. An equitable system is based upon both. Systems are also viewed as being fair based upon their impact on certain income groups. Regressive tax systems hurt lower income individuals requiring them to commit a greater share of their income to pay fees or taxes. When a large portion of income is used for essential goods and services such as food and housing, taxes levied against those products have a greater impact on low income groups.
Progressive systems require higher income people to pay a greater share of their income for taxes.
Idaho s system has been judged to be fairly progressive by a number of different studies. Figure 3 illustrates the rising percent of income that is paid in income taxes and the somewhat regressive effect of the sales tax and auto taxes. The study focuses on an annual comparison of the tax burden for the largest city of each state. The study focuses on a family of four at four different income levels. The values compared are income, property, sales and automobile taxes.