The wealthy and low-income people stand a better chance of being audited than the typical middle-class family, which is paying the lowest share of its income to the Treasury since 1957.

Rich, poor and the middle class all are affected by one tax trend — the 17,000-page, 2.8 million-word tax code is more complex than ever. One estimate is that it now takes 28 hours and six minutes to tackle the Internal Revenue Service's 1040 form and do the necessary record keeping.

This year's filing deadline is midnight Monday for most of the country.

IRS data and reports from several tax research organizations depict a tax system that does not treat everyone equally but is, by far, the single biggest source of government paperwork and red tape.

``An abomination,'' Treasury Secretary Paul O'Neill calls it.

Consider IRS audits. Individuals making $100,000 or more and those making $25,000 or less are much more likely to face an audit than the tens of millions in between. High-income people tend to have more complicated returns that invite more audits; about 0.69 percent of all these returns were audited in 2001.

Those making under $25,000 usually have simple returns, yet about 0.40 percent were audited last year. That is almost twice the rate of taxpayers in the middle-income range and is largely attributable to the earned income tax credit, effectively a low-income refund program on which the IRS has focused attention to cut down on mistakes and fraud.

When audits related to that tax credit are not included, the rate for those earning under $25,000 drops to 0.15 percent, the IRS says.

For all taxpayers, the audit rate in 2001 was 0.58 percent, a slight rebound from the year before but far lower than in previous years. One reason for that is the 1998 IRS reform law that attempted to make the agency friendly to taxpayers.

``We don't see the unreasonable and harassing tactics we saw in the past,'' said Jennifer Prager Sodaro, an attorney who specializes in representing people accused of tax crimes.

The middle class is enjoying the lowest tax burden in decades, according to the Center on Budget and Policy Priorities, a government research group focused on the lower and middle classes.

Using government data, the center projects that a family of four making exactly the median income — $64,600 a year in 2001 — paid 6.8 percent of its earnings in federal income taxes. That compares with 10.3 percent during the 1980s for the same median-income family and is the lowest rate since 1957.

The decline was taking place before Congress passed President Bush's 10-year, $1.35 trillion tax cut, which further reduced the middle-class burden in the early years of that cut. In his Saturday radio address, Bush said taxpayers have already benefited from $57 billion in tax relief from that law and ``the best news is that tax relief is continuing this year.''

Average tax refunds this year are running about 12 percent above the year before, in part because the child tax credit targeted at middle-income people was raised from $500 to $600 by the tax relief legislation. The average refund through April 5 was $1,954.

Taxpayers at all income groups must deal with an ever more complex tax system. The White House budget office estimates that in 2001, Americans spent 1.5 billion hours on federal paperwork — 80 percent of it dealing with tax forms.

Roger Harris, an enrolled agent licensed by the Treasury Department to practice before the IRS, said the 10,000-member National Association of Enrolled Agents is seeing more clients than ever.

H&R Block, the nation's largest tax preparation firm, recently reported a 4.4 percent increase in returns prepared, with fees running 12.1 percent above last year.

``More and more, taxpayers are opting to leave return preparation to the professionals because continued tax law complexity makes it difficult for them to prepare their tax returns with confidence,'' Harris said.

The single new line on the tax forms about how to account for last year's tax rebate checks of up to $600 has triggered more than 4 million errors, according to the IRS.

The National Taxpayers Union, a nonpartisan group that advocates lower taxes, calculated the 1040 form preparation and record keeping time, including commonly used schedules, of 28 hours, six minutes. That's an increase of more than an hour compared with last year and 40 percent more time-consuming than in 1997.

The 122 pages accompanying the standard 1040 form is triple the number in 1975.

``Sixty-five years ago its instructions were just two pages long,'' said David Keating, senior counselor at NTU.

Beginning Monday, the Bush administration planned to issue a series of reports on how to simplify the tax code. Many of these proposals might take years for Congress to implement and might encounter resistance if they force lawmakers to make unpleasant political choices among groups now getting tax breaks.

``Only fundamental tax reform might be a strong enough lifeline to save us from drowning in a sea of tax law,'' Keating said.

Yet advocates for replacing current tax law with a flat tax or a consumption tax have made little progress.