If you consider income tax liability alone, the average effective federal tax rate for people with incomes between $40,000 and $50,000, for instance, is just 3.2%, according to Tax Policy Center estimates. (In measuring income, the center uses gross income and adds to it other forms of compensation, such as the money your employer contributes to your retirement savings.) The lowest income families actually have negative average effective tax rates when income tax liability alone is measured. For families making $50,000 to $75,000, the effective tax rate is 5.7%. From $75,000 to $100,000, it's 7.2%. And if you make $200,000, it goes up to 9.9%.