effective income tax rate. Definition. The actual rate at which a taxpayer pays taxes on income accounting for all taxes and offsets. The rate is calculated by dividing the total of all taxes paid, less offsets, by the total taxable income. The effective rate is typically lower than the tax bracket, which is currently based on a progressive rate scale. For example, a person in the 28% tax bracket who paid a total of state and federal taxes of $13,000 on $100,000 of taxable income has an effective tax rate of 13%.