with respect to we are now at the point of determining the tax rate that is applied to taxable income. A bracket system is used to define tax rates. The taxable income scale is divided into segment, and be law specifies the marginal tax rate that applies to income in that segment. Actually, there are four different rate schedules, one each for married couples who file together, married people who file separately, unmarried people, and singe people who are heads of households.