Once a year, Jean Edwards and her friend Irene get together and chat about their lives -- while Edwards, a tax preparer for H&R Block Inc., does Irene's taxes.

They gossiped about several things at their annual session in Block's K Street office last week: Irene had taken a trip to New York, Edwards' daughter was ill, and the tax laws had changed.

That last development nearly cost Irene $180 in additional taxes.

Edwards initially overlooked the larger standard deduction available this year for taxpayers who are over 65. She detected the error after checking with colleagues. "I'm still learning as I go," she said.

Welcome to the Tax Reform Act of 1986, the law that confuses even the pros.

This year, the tax returns and forms that more than 100 million American taxpayers will file by April 15 incorporate the myriad alterations in the tax code that Congress enacted in 1986. By Monday, the deadline for taxpayers to receive their wage and income statements, the nation will be embarked on what could become the most widely shared financial trauma since the 1979 energy crisis.

The ambitious goal of the sweeping 1986 tax law revision was to create a tax system that would be fairer, more efficient -- and simpler. For some taxpayers, such as those who take the standard deduction or were dropped from the tax rolls by the law's changes, 1988 tax filing indeed may be easier than it was last year.

And the complexity will for some people be offset by the tax reductions that the new system will grant to a majority of taxpayers. Irene (who asked that her full name not be used) was satisfied. She paid $71 less in 1987 than in 1986.

But many, many others will find out soon that tax revision can mean major tax complications.

"Everybody agrees this will be the worst, most complicated tax season anybody has gone through," said Andrew S. Lang of the Bethesda accounting firm Raymond A. Lang & Associates.

"I think confusion is running very high," said Thomas M. Bloch, president of the tax operations division of H&R Block.

Tax preparers from firms of all sizes say both professional preparers and the average citizen are very likely to make mistakes this year, for a number of reasons:

The "simplification" law has spawned 49 new tax forms, plus revisions in another 200 or so. The basic 1040, 1040A and 1040EZ tax returns are relatively unchanged, and a few tax forms have been eliminated by the law. Most of the 49 new forms are only for businesses. But many individuals still will have to cope with at least two or three new forms, as well as new items in the basic return and schedule A, which lists itemized deductions.

Many of the law's changes will affect millions of taxpayers, not just the ultrarich who can afford high-priced accountants. Such widely used deductions as those for home-equity loans, two-income couples, union dues and individual retirement accounts have disappeared or require new calculations.

Most people remain unaware of the provisions of the new law, despite extensive efforts by the Internal Revenue Service to inform them and to urge early preparation of tax returns. In recent years, taxpayers have been filing their returns closer and closer to the April 15 deadline -- a trend that could lead to chaos when combined with the additional time it will take people to fill out the unfamiliar forms.

This confusion is expected to send millions flocking to accountants and other tax preparers -- few of whom are thrilled about it.

"I'm finding myself having to soothe my poor clients," said Edward L. Snyder, a partner in the accounting firm Snyder, Newrath & Co. in Bethesda. "They're not blaming us yet, but they could."

The blame may come when the customers get the bill. Accountants say that increases in nonbillable training time, more demand for their services and the greater complexity of tax forms mean that having taxes done will cost 25 percent to 50 percent more than a year ago.

"There is a group of people who have been pushed over the edge by this latest wave of complexity, and now are looking for accountants," said Jeffery P. Capron of the firm McQuade & Capron in the District. "It was never worth it {for them} before to spend $300 to get their taxes prepared. This year, $300 is more like $415."

Using everything from the Goodyear blimp to commercials based on horror movies, the Internal Revenue Service has undertaken its most extensive public relations campaign ever to counter this potential wave of frustration, confusion and anger.

More than 4,300 question-answering telephone lines will be open this year, a 30 percent increase from 1987. The number of employees in the taxpayer-service area has been increased from 3,400 to 4,500, and the workers have been more extensively trained in the new law. More than 16 million copies of Publication 920, Explanation of the Tax Reform Act of 1986 for Individuals, have been distributed to taxpayers.

"It's our all-time best-seller," said spokesman Rod Young.

The Goodyear blimp floated over Houston, trailing a sign that said: "Make your taxes less taxing" with the number of the local office. And nationwide television commercials, showing blue lights and strong winds exploding from a desk containing tax forms, urge Americans to file early to avoid "a private horror of your own making."

IRS agents are calling their own telephone lines to ensure that the service is giving taxpayers the right answers. But early indications are that the tax collectors are a little confused about their own law.

So believes Stephen P. Farber, a Maryland clinical psychologist who called the IRS three times to see whether he was required to fill out a new form for interest on certain home loans and refinancings. (Fewer than a million taxpayers will have to fill out the form, but an additional four million need to look it over to be sure they don't qualify.) On Farber's first call, the person who answered said he should fill out the form. Then he changed his mind and said no after Farber gave him additional details. Then he said yes again, after he learned more. The second person Farber called first said yes, then no. The third time, Farber got disconnected as his call was transferred.

"The funny part is, I kind of supported the notion of having the tax code simplified," Farber said. "This is not simplified."