In '06, Rich Earned More, Paid Less Tax

In 2006, the 400 richest Americans had an average income of $263 million, a 23 percent jump over the previous year, the Internal Revenue Service says. That same year, the very wealthy paid, on average, an effective tax rate of 17 percent — the lowest in 15 years.

Bill Gale, co-director of the Tax Policy Center at the Brookings Institution, says the numbers are "stunning confirmation" that there has been a big rise in the income and wealth of the wealthiest Americans at least until 2006.

Gale says the richest Americans had a relatively low tax burden because most of their income is in the form of capital gains, which are taxed at very low rates relative to wage income.