he job is done, and the homeowner reaches into her purse for her checkbook.

But the handyman doesn't want a check. "Would you mind giving me cash?" he asks quickly, and then, after an awkward moment, he mumbles something about banks that are closed and groceries that are needed.

The homeowner hunts through her coat pockets, reaches into her daughter's cache of babysitting money, and eventually scares up the dollars. The handyman says thank you and leaves. The homeowner says you're welcome and shakes her head. Welcome to the underground economy.

The man has not said that these $35 are his tax-free. The woman has not asked. But she silently figures the odds against any portion of these dollars going to the Internal Revenue Service. A hundred to one. A thousand to one.

The homeowner would not ordinarily even notice. She doesn't think about the IRS every time she leaves cash on a restaurant table or a drugstore counter or a corner stand.

But it is mid-April, and she has just tallied up her taxes. According to her accountant, she has transferred enough money to the U.S. Treasury to support an entire community in Bangladesh. In 1982, a piece of a tank or missile will be built in her honor.

Now her after-tax dollars are his untaxed dollars.

The homeowner still finds this subterranean tax-free ethic striking. She grew up in the era when everyone believed that the IRS, like the boogeyman, would get you. She grew up in an era when the people who didn't pay their taxes had names and futures like Al Capone.

Now, if the IRS's own study is to be believed, 5 percent of the labor force works off the books. People who are self-employed report only about 60 percent of their incomes. Even farmers, the purity figures of our culture, fail to report 30 percent of their income. For one reason or another, the government isn't getting its share of $135 billion.

The members of this underground apparently don't even feel guilty anymore. For years the government has kept a Conscience Fund for the tax evaders who came down with a case of qualms and wanted to set things right. In 1980, Americans voluntarily sent the fund $126,000; but in the first nine months of 1981, they sent in only $4,465.

Were we more honest in the past, or just more frightened? In the mid-'60s the IRS audited 5 percent of the taxes filed. But in the 1980s, auditing is down to about 2 percent.

Are we less honest in the present, or just more alienated? In the mid-'60s there was an ethical judgment against tax "cheaters." In the mid-'80s that judgment has become, uh, relative.

The homeowner conducts an unscientific poll among people she knows who have also had encounters with members of the underground economy. She samples their attitudes.

There is hostility from those whose salaries, like hers, come in paychecks with taxes already deducted. The wider the underground spreads, they know, the more it will cost the aboveground. But there is also a kind of sympathy, even collusion.

One woman who pays her cleaning lady in cash and asks no questions calls it, ironically, a tax shelter for the poor. A man who paid cash to have his house painted calls it a tax cut for the working class.

One person reasons that taxes are too high anyway. Another reasons that the rich pay too little anyway. This, they both shrug, just balances wrongs a little.

Many excuse their own attitude as a political protest against weapons or business lunches or unfairness. Many feel a certain tingle of pleasure in bucking the system by denying the system its bucks. Not a one of them wants to be his brother's tax collector.

The homeowner sifts all this data through her mind as she walks to the store for money to repay the loan filched from her daughter's cash cup.

The underground economy has finally surfaced in her life. Willy-nilly, the homeowner has become an accomplice. She has joined the co-conspirators who are numbered in the thousands, even the millions. Still, she can't work up a gripe against the handyman.