by David Cay Johnston

Income inequality grew significantly in 2005, with the top 1 percent of Americans - those with incomes that year of more than $348,000 - receiving their largest share of national income since 1928, analysis of newly released tax data shows.The top 10 percent, roughly those earning more than $100,000, also reached a level of income share not seen since before the Depression.

While total reported income in the United States increased almost 9 percent in 2005, the most recent year for which such data is available, average incomes for those in the bottom 90 percent dipped slightly compared with the year before, dropping $172, or 0.6 percent.

The gains went largely to the top 1 percent, whose incomes rose to an average of more than $1.1 million each, an increase of more than $139,000, or about 14 percent.

The new data also shows that the top 300,000 Americans collectively enjoyed almost as much income as the bottom 150 million Americans. Per person, the top group received 440 times as much as the average person in the bottom half earned, nearly doubling the gap from 1980.

Prof. Emmanuel Saez, the University of California, Berkeley, economist who analyzed the Internal Revenue Service data with Prof. Thomas Piketty of the Paris School of Economics, said such growing disparities were significant in terms of social and political stability.

"If the economy is growing but only a few are enjoying the benefits, it goes to our sense of fairness," Professor Saez said. "It can have important political consequences."

Last year, according to data from other sources, incomes for average Americans increased for the first time in several years. But because those at the top rely heavily on the stock market and business profits for their income, both of which were strong last year, it is likely that the disparities in 2005 are the same or larger now, Professor Saez said.

He noted that the analysis was based on preliminary data and that the highest-income Americans were more likely than others to file their returns late, so his data might understate the growth in inequality.

The disparities may be even greater for another reason. The Internal Revenue Service estimates that it is able to accurately tax 99 percent of wage income but that it captures only about 70 percent of business and investment income, most of which flows to upper-income individuals, because not everybody accurately reports such figures.

The Bush administration argued that its tax policies, despite cuts that benefited those at the top more than others, had not added to the widening gap but "made the tax code more progressive, not less." Brookly McLaughlin, the chief Treasury Department spokeswoman, said that this year "the share of income taxes paid by lower-income taxpayers will be lower than it would have been without the tax relief, while the share of income taxes for higher-income taxpayers will be higher."

Treasury Secretary Henry M. Paulson Jr., she noted, has acknowledged that income disparities have increased, but, along with a "solid consensus" of experts, attributed that shift largely to "the rapid pace of technological change has been a major driver in the decades-long widening of the income gap in the United States."

Others argued that public policies had played a role in the shift. Robert Greenstein, executive director of the Center on Budget and Policy Priorities, an advocacy group for the poor, said that the data understates the widening disparity between the top 1 percent and the rest of the country.

He said that in addition to rising incomes and reduced taxes, the equation should take into account cuts in fringe benefits to workers and in government services that middle-class and poor Americans rely on more than the affluent. These include health care, child care and education spending.

"The nation faces some very tough choices in coming years," he said. "That such a large share of the income gains are going to the very top, at a minimum, raises serious questions about continuing to provide tax cuts averaging over $150,000 a year to people making more than a million dollars a year, while saying we do not have enough money" to provide health insurance to 47 million Americans and cutting education benefits.

A major issue likely to be debated in Congress in the year ahead is whether reversing the Bush tax cuts would slow investment and, if so, how much that would cost the economy.

Mr. Greenstein's organization will release a report today showing that for Americans in the middle, the share of income taken by federal taxes has been essentially unchanged across four decades. By comparison, it has fallen by half for those at the very top of the income ladder.

Because the incomes of those at the top have grown so much more than those below them, their share of total income tax revenue has risen despite the reduced rates.

The analysis by the two professors showed that the top 10 percent of Americans collected 48.5 percent of all reported income in 2005.

That is an increase of more than 2 percentage points over the previous year and up from roughly 33 percent in the late 1970s. The peak for this group was 49.3 percent in 1928.

The top 1 percent received 21.8 percent of all reported income in 2005, up significantly from 19.8 percent the year before and more than double their share of income in 1980. The peak was in 1928, when the top 1 percent reported 23.9 percent of all income.

The top tenth of a percent and top one-hundredth of a percent recorded even bigger gains in 2005 over the previous year. Their incomes soared by about a fifth in one year, largely because of the rising stock market and increased business profits.

The top tenth of a percent reported an average income of $5.6 million, up $908,000, while the top one-hundredth of a percent had an average income of $25.7 million, up nearly $4.4 million in one year.
Copyright 2007 The New York Times Company