The report, based on IRS and Census Bureau data, comes as the Occupy Wall Street movement protests corporate bailouts and the gap between the haves and have-nots. Demonstrators call themselves "the 99 percent."
"The distribution of after-tax income in the United States was substantially more unequal in 2007 than in 1979," CBO Director Doug Elmendorf said in a blog post. "The share of income accruing to higher-income households increased, whereas the share accruing to other households declined."
The top 1 percent made $165,000 or more in 1979; that jumped to $347,000 in 2007, the study said. The income for the top fifth started at $51,289 in 1979 and rose to $70,578 in 2007. On the other end of the spectrum, those in the 20th percentile went from $12,823 in 1979 to $14,851 in 2007.
The report also found:
* The top 20 percent of the population earned 53 percent of after-tax income in 2007, as opposed to 43 percent in 1979.
* The top 1 percent reaped a 17 percent share of all income, up from 8 percent in 1979.
* The bottom 20 percent reaped just 5 percent of after-tax income, versus 7 percent in 1979.