Begin Working Part Time With Full-Time Planning : Employment: Two questions before quitting a full-time job: Can you afford it? Who will do the work you leave behind?

Now that most adults are in the work force, millions of Americans have something else in common: They want to work less. If you’re one of them, you know there’s only one big question about switching to part-time work.

The question, of course, is can you afford it?

That depends on how you want to live, how much your spouse makes, and how much you believe you can get by on. In many cases, whether you can afford to work part time instead of full time is really a host of questions about what’s important to you.

Could you live in a modest apartment instead of a spacious house? Are you willing to move someplace where everything’s cheaper? Will you die of jealousy working part time while your spouse’s full-time career plows full steam ahead? Do you think you are what you do?

Some people don’t get to wrestle much with these issues. If you’re the sole support of two children and make $12 an hour, you can’t afford to work part time. That’s probably so even if you have a spouse who earns the same.

“This is a two-wage economy,” warns spokeswoman Barbara Otto of 9 to 5, the National Assn. of Working Women. “There are very few women--or men--in this country who have the luxury to choose not to work, and very few who have the luxury of not working full time.”

But that’s not entirely true. The Bureau of Labor Statistics says nearly 21.5 million Americans were working part time in 1992. While many of them were unable to get full-time work in the recession, 70% of U.S. part-time workers said they were keeping limited hours by choice.

Many middle-class people do in fact have some options here, particularly if theirs is a two-income household and only one wage-earner hopes to go part time.

Part-time employment seems to work best, in fact, when one member of the couple works at a firm with good health and other benefits that can be carried over to cover a spouse and children.

“You have to think through the trade-offs, and the financial trade-off is one,” said Barney Olmsted, co-director of New Ways To Work, a Bay Area nonprofit research group.

Face it: Working less means getting used to living on less. It can affect your ability to save over the long haul for such things as your child’s college education or your retirement. And don’t forget health insurance.

“People who are considering this have to know what will happen to their benefits,” advises Rose Krupp-Ayala, who shares the head public relations job at the Los Angeles chapter of the American Diabetes Assn.

As a part-timer working fewer than 20 hours a week, Krupp-Ayala doesn’t meet the ADA’s qualifications for employer-paid health coverage. Consequently, like more than a third of the nation’s part-time workers, she had to get her own.

Federal law requires employers to make Social Security contributions and open pension plans to employees who work more than 1,000 hours a year. But other benefits are more iffy, especially those who don’t meet that 1,000-hour threshold.

In 1988, for instance, New Ways to Work and the Conference Board, a business organization, surveyed 521 of the nation’s largest corporations and found that:

* 56% offered health benefits to part-timers.

* 27% offered health benefits to those working less than 1,000 hours a year.

* 13% offered no part-time benefits at all.

Potential part-timers need to find out what benefits are available at their firm, get it in writing and take it into account at decision time.

Some jobs are more suited to part-time work than others, says Linda Marks, a San Francisco consultant who advises workers considering switching from full-time to part-time hours.

Some industries--retailing and clerical work, for instance--have a long history of hiring part-timers. Other fields, such as banking, insurance, transportation and law, have become more flexible lately about part-time work too. Even some managers have moved successfully to part-time hours, although they remain rare.

“You have to go through all the tasks and responsibilities of the position” before proposing a cut in hours to your boss, Marks says. “Are you going to try to do the whole job part time? I hope not. Which parts are you not going to be doing, and how will they get done? Will you hire a free-lancer in to do the work? Can someone job share with you?

“That is the place where most people fail,” Marks adds. “They say, ‘I want to work three days a week,’ but they don’t figure out who’s going to do the rest of the work. Consequently, they end up doing 40 or 50 or 60 hours worth of work for a part-time salary, and they feel resentful.”

Consider the professional ramifications. What do you want to be doing three years from now? What will working part time do to this goal? Will your career suffer if you aren’t in the office every day, to network with co-workers and customers?

And finally, prepare yourself for the employer’s eternal question: What’s in it for me?

“Employers want to know, is this going to cost me more?” Marks says. “If I let you do this, won’t everyone else want to too? What if I need you, and you aren’t around? Managers can’t work part time. Employers worry that things will fall between the cracks.”

But there are answers to those questions, she adds. Job sharing, for instance, doesn’t have to cost the employer a dime if the salary and benefits are prorated and the employer uses a full-time-equivalent head-count system for accounting purposes, so that two part-timers can be counted as a single employee.

Nonetheless, you’re likely to get resistance from management.

“It didn’t work for me,” recalls Kim Robertson, a Huntington Beach account executive for a financial planning firm who asked three years ago to go part time so she could have more time with her two toddlers.

“The president finally said I could go part time if I wanted, but I’d have to work in a lower position,” she recalls, adding: “It would have been like starting at the bottom again.”

As it turned out, Robertson says, the obstacle was for the best--within a few months of her request, she and her husband divorced, and she needed the full-time salary to survive. If she had it to do over, however, she says she would have been more confident in making her pitch, and would have made sure she had some leverage, such as a job offer at another firm.

Krupp-Ayala and her job-share partner, Lynn Winter Gross, had a slightly easier time.

“We got a number of no’s before we finally got a yes,” Winter Gross says. “Interestingly enough it was from a man who, it turned out, had a new baby himself and really understood the need.”