For Irwin Schiff, April is just another pleasant spring-time month, because while everyone else is paying taxes, he's ignoring the IRS - and so far getting away with it. I don't worry about it all," Schiff, slightly Paunchy 49-year-old insurance executive from New Haven, Conn., says gleefully. "What should I be nervous about? I love April - have big parties this time of year."

If all this sounds a little blase coming from a man says he hasn't given Uncle Sam a dime since 1973, Schiff explains he has ironclad legal reasons not to pay taxes - reasons, he says, the IRS is afraid to challenge in court. They wouldn't dare," he says, riffling through a stack of documents and arguments. "I know more about this stuff than any judge in the country," (The IRS maintains that cases such as Schiff's may not go to court for as many as six or seven years.)

Schiff's recipe for escaping the IRS stems in part from his own strict interpretation of the Constitution. The income tax is illegal, he insists, because of the Fifth Amendment proviso against self-incrimination - and, of course, your 1040 form can be used against you. But the central part of his antitax message doesn't have anything to do with the legality of the IRS - it pertains, he says, to the currency with which we pay them.

When the United States removed what Schiff calls "the pretense of gold and silver backing from the dollar" in 1971. Schiff says the currency lost all its value. The once mighty dollars became what he calls "greenies" - worthless pieces of paper, he says. Thus, Schiff argues, although he made close to $100,000 in "greenies" last year, he made nothing in terms of real, metal-backed dollars. No real dollars, no real income to tax - it's as simple as that, Schiff believes.

"In 1971 they abolished the dollar," Schiff says angrily as he waits to appear on the local ABC news show here. "Does Congress determine the value of this stuff green?" he asks holding up a wad of bills like it was a head of lettuce. "What's the value of a floating dollor? Nothing!"

Schiff is obsessed with the notions that our economy and government are based on air. He spreads the word at special seminars to thousands of citizens - at 25 greenies a shot. At the same time he's conducting a coast-to-coast road show in newspapers and on broadcasts.

Shuffling from city to city, station to station, Schiff never manages to lose his sense of outrage. Ask him what he thinks of the weather and he'll cite consitutional law. Even while makeup women pat his face with orange powder and comb his few remaining strands of gray hair, he's arguing.

Millions watched Schiff April 6 on Tom Snyder's "Tomorrow" show, hammering away on how to avoid paying up by Monday at midnight. Snyder was impressed. The audience, staff producer Bob Carman believes, may have been one of the largest in "Tomorrow's" history. At the end of the show Snyder even joked that his staff was so impressed with Schiff that they wouldn't be filing with the IRS this year either.

But I am," Snyder insisted.

The next morning, nearly 2,000 miles from NBC's Burbank studios, Chicago radio commentator Paul Harvey mentioned Schiff's appearance on the "Tomorrow" show and the staff's reputed tax rebellion on his nationally syndicated broadcast. Synder, it turned out, was just having a little joke at his staff's expense, but the public didn't know that. "Our telephones nearly broke the next morning," recalls "Tomorrow's carman.

This week Schiff made a return Performance.

Synder has set aside an hour for Schiff and James Schanake, a former federal prosecutor and now a tax lawyer practicing in Oakland, Calif. The portly former fed tries to counter-point Schiff but can't hold the floor for long against the tax zealot. By the end of the show Schanake is reduced to watching while Schiff and Synder battle it out.

"You're going to jail," Synder insists. "Yes, you are." Snyder says that the tax rebel is a dangerous man because he is leading other poor souls into trouble. Schiff repeats that after four years of nonpayment he hasn't even had a handkerchief repossessed. "Just give them time," Snyder replies.

The hostile confrontation leaves Schiff contentious as ever. "Tom Snyder, I'm afraid to say, is afraid of a big audit. "He still doesn't know he really doesn't have to be afraid of the IRS, but he's intimidated. If he comes to one of my seminars, he'd know that."

"That's perfectly ridiculous," Snyder's man, Carman said of Schiff's contention. "If Tom took a different attitude it was all in the interest of fairness. I think Tom thought a lot of people were taken in the first time. He didn't want people to be duped - and get in trouble."

The man who may really be in trouble, however, is Irwin Schiff.Despite his broad claims of consitutional protection, officials at IRS headquarters in Washington, while carefully avoiding mention of Schiff's individual case, doubted any tax protestor could remain free from prosecution indefinintely.

Larry Batdorf, spokesman for the IRS, said it was entirely possible for someone not to be audited after hour years of not paying taxes. "It can take years," Batdorf explained. "It depends on the complexity of the case and the extent of the violation." He added that it might take as much as six or seven years before a case like Schiff's would come to court.But that, he said, didn't mean the investigative process wasn't already under way.

But Irwin Schiff isn't afraid of the IRS. He has already made plans for an income-taxless nation, a return to hard money and rugged individualism. For Washington, Schiff mourns, this could mean a loss of thousands of government jobs. Federal department, such as Labor and Agriculture, would be completely disbanded, the latter converted into a nice youth hostel.

No ruling, even the unanimous opinion of the Supreme Court, would deter Schiff from believing in the righteousness of his views. "Just because the courts or anyone else says anything doesn't mean I'm wrong." he says, his face still smooth with makeup. "The courts are politically expedient. I mean, if the courts rule an elephant is a chicken, does that mean an elephant is a chicken?"You know what I mean."