A new genre of lobbyist is stalking Capitol Hill. Some of America's best-known authors are trying to do what most big-time influence-peddlers could not: restore a tax break wiped out by the Tax Reform Act of 1986.

Undeterred by the failure of such interests as banking, oil, insurance and manufacturing to persuade Congress to retain their pet deductions last year, a small army of writers has spent the last two months working to overturn an obscure footnote to the tax law's report. That footnote limits the deductions they now take for the expenses incurred in writing books. If the authors do not succeed, they say, their taxes will rise sharply, most will find it harder to make a living and literature will suffer.

Among the writers-turned-lobbyists wooing members of the tax committees in the House and Senate are David Halberstam, Robert Massie, William McPherson, Christopher Buckley, J. Anthony Lukas and George J.W. Goodman, who writes as Adam Smith. In classic special-interest style, the authors also have hired their own Washington lobbying firm and launched a mail campaign that has generated at least 4,000 letters.

For neophytes at the persuasion biz, early indications are they aren't doing too badly.

"One thing you can say about Capitol Hill, people do read," said Rep. Thomas J. Downey (D-N.Y.), who is on the authors' side. "When somebody like Halberstam shows up in the office, people know him. I suspect America's great authors will get to know the members of the Ways and Means Committee on a first-name basis as this goes on."

Some of the fledgling lobbyists already know their quarry and are using this fact to their advantage. Halberstam, for instance, was able to collar Sen. Bob Packwood (R-Ore.) on the Senate subway to make his case, and to set up a meeting with Sen. Bill Bradley (D-N.J.), a chief author of the tax-revision law, who agrees with the writers that the provision is unfair.

"By traditional lobbying standards, we have one of the smallest and poorest offices imaginable," Halberstam said. "The only leverage we have is our reputations and the possible social value of what we do."

Like many legislative tax battles, this one is both emotional -- it's "a bloodletting issue for us," said Helen Stephenson, executive director of the Authors Guild -- and complex. Under the old tax code, authors could deduct the expenses of writing books or articles the year they laid out the money, even if the book were not published for years. The new law would only let the deductions be taken when the book or article began to generate income -- often long after the bills actually are paid.

In other words, a $5,000 research trip in 1987 could only be deducted when the published work hit the stands and brought in money -- in, say, 1992. Even then, authors would be allowed to take only part of the deduction each year, until the book made all the money it was going to produce -- necessitating, in effect, a prediction of total profits before one copy is sold.

"I have written plays and other works as long as 40 years ago which, since I was then an unknown author, earned little or no money, but which now create far more income than they did so long ago," playwright Arthur Miller wrote to his congressman and senators. "Under present tax law, I should have had to wait 40 years to deduct necessary expenses incurred in the creation of these works."

"We are going to be required to forecast income, which no author can do," said Massie, whose books include "Nicholas and Alexandra" and "Peter the Great." "How do I know when I sit down to write a book how much money it will make?"

The idea behind the footnote -- inserted without legislative discussion into the conference report on the tax law by congressional and Treasury Department staffers -- is classic tax theory: Income and deductions for the same product should come at the same time.

During their meetings with authors, the Treasury and congressional aides responsible for the footnote defended its intent. Under the old law, they explained, writers could defer paying some of their taxes for years -- even though they produced "tangible" goods that, for tax purposes, were no different from a car or an appliance. General Motors, the theory goes, shouldn't write off the full cost of its machine tools until they are worn out and the cars it has made are sold.

But what's good for GM may not be right for writers, who don't have the steady production of a manufacturer or the accounting finesse of the boardroom.

"They are treating authors the way they treat a manufacturer of toasters," said William McPherson, author most recently of "The Sargasso Sea."

The footnote also appears to cover such fields as screen writing, photography, songwriting and dance choreography, and book publishers have a related problem with it. But white-collar professionals are not included in the change. Lawyers can continue to deduct their expenses during the year they are incurred, even if the case they're working on isn't decided for a decade. Even large companies can deduct certain expenses in one year while amortizing others over several years.

"Unlike the widget makers, unlike GM or farmers or small retailers, the way this is written every single direct or indirect cost of researching and writing a book must be amortized," said Stephenson of the Authors Guild. "There is not one single thing we do that can be deducted currently."

She and Massie, president of the authors' organization, have explained this to nearly every member of the Senate Finance Committee and perhaps two-thirds of the House Ways and Means Committee. Legislators have been delighted to meet with them, although not just because they wanted to discuss the intricacies of Section 263A and its accompanying footnote.

Sen. David H. Pryor (D-Ark.) regaled his visitors with tales of his days as a newspaper publisher. Sen. John Danforth (R-Mo.) confessed he was probably the only senator never to have written a book. "Tell me," he asked, "how do you start?" Sen. Daniel Patrick Moynihan (D-N.Y.), who has published 14 books and still gets royalty checks from several, sympathized with the writers and vowed to help repeal the footnote.

No one denies that authors' star appeal helps attract the interest of legislators.

"I've got a request in to see Robert Caro," joked Rep. Downey. "If I'm going to do this, I want to meet all my favorite authors and ask them all the questions I've always wanted to ask."

The authors have bumbled occasionally in their new avocation. At a meeting of the Washington Independent Writers group to plot lobbying strategy last month, lobbyists-to-be eagerly perused a list of Ways and Means Committee members and staffers -- a list replete with wrong names and omissions. And they timed their efforts to contact members of Congress with tax-drafting that was to begin later that week, not realizing that the committee was writing a tax-increase bill and would not take up the bill to make technical corrections to the new tax law for another month.

But as might be expected, authors are making great headway in one kind of lobbying: writing letters. Perhaps 4,000 to 5,000 protests have been sent to Capitol Hill offices in response to mailings by the Authors Guild, Washington Independent Writers, PEN and the screen writers' guild. Not just big names, but small-time mystery, romance, adventure and horror writers have pleaded their cases.

Evan and Ann Maxwell, for instance, said it would cost $5,000 more in accounting fees to allocate their expenses among the eight mystery and historical-romance novels they currently have under contract, not to mention projects in development. The Authors Guild, fearing it will be perceived as lobbying for a fat-cat provision, points out that the median income from writing for its 6,500 members is $7,900 per year.

"There are maybe 200 writers who could possibly be considered fat cats, people who actually make money year after year. There are 15,000 or 16,000 who make a living at it," said McPherson, who made his lobbying rounds to show members of Congress the law's effect on what he called a "low-rent author."

Most of the meetings between literature and legislature have been arranged by Liz Robbins Associates, a firm retained by the Authors Guild that lobbied on several tax issues during last year's consideration of the tax bill. But even with high-powered assistance, the authors are bit players in the struggle nearly every Washington operative is engaged in: to use the technical-corrections bill to mitigate the tax law's damage. "Three-quarters of the free world," says Downey when asked who is lobbying for a technical correction. "It's easier to figure out who hasn't lobbied me than who has."

Among the lobbyists jostling for a technical correction -- the bill will not be considered until the fall -- the authors may bear the unique distinction of speaking for themselves, rather than as hired guns. But the idea of pleading a case before Congress still makes some of them a bit uneasy.

"It was very odd," Halberstam said, in describing his lobbying experiences. "I had never lobbied. I don't think reporters should ask for things in general. But I don't think there was a conflict of interest per se. These people are outside our main magnetic field. And I think this provision is injurious and unfair.

"I will survive, Bob Massie will survive. But it is a lot harder for someone 30 years old who is coming behind us. It's one more obstacle in what is already a difficult field."