Almost as certain as death and taxes is the public's feeling that the U.S. income tax system is not fair. An Ipsos Poll released this week found almost six of 10 people, 58 percent, say the system is unjust, a number that is virtually unchanged from two decades ago.

People think the middle class, the self-employed and small businesses pay too much in taxes, the poll found. And they think those with high incomes and big businesses don't pay enough. The survey was conducted in the days before the mid-April deadline for filing income tax returns.

Dissatisfaction with the tax system remains high after numerous changes in tax law since the late 1980s.

The Reagan administration led a tax overhaul two decades ago that significantly lowered tax rates and eliminated or reduced several deductions. The first President Bush abandoned his "read my lips, no new taxes pledge" in a 1990 budget deal that raised taxes.

The Clinton administration won passage in 1993 of a deficit-reduction measure that blended tax increases, budget cuts and rebates for the working poor.

And the second Bush administration pushed successfully for tax cuts that lowered the top income tax rate to 35 percent and slashed tax rates for individuals and manufacturers.

People were most likely to think the middle class is paying too much in taxes, according to the poll.

More than half, 58 percent, said middle-income families pay too much income tax and people were almost as likely, 54 percent, to say that about low-income families.

Six in 10 said high-income families were paying too little in taxes. But 20 years ago, almost eight in 10 said high income families were paying too little.

Tax cuts for the wealthy have been at the heart of a bitter partisan tax debate during much of this Bush administration.

The poll of 1,005 adults was conducted April 11-13 by Ipsos, an international polling firm, and has a margin of sampling error of plus or minus 3 percentage points.