Examines effective federal tax rates -- tax liabilities measured as a percentage of income -- over the 1979-1997 period for all households and for quintiles, or fifths, of the income distribution. The analysis uses a comprehensive measure of household income that encompasses not only cash income but also the value of benefits received in kind, such as health care and food stamps. The study provides information on the four major federal taxes: individual and corporate income taxes; social insurance, or payroll, taxes; and excise taxes. It also considers the combination of the four. Illustrated with graphs and tables.