When one of a two-earner team stays home: planning counts!

The upholsterer was busy in the family room, measuring for new slipcovers, so Jeanette Webb talked about her family finances in the kitchen instead. Now that she's working again, the Webbs are spending money on slipcovers, but that wasn't so two years ago, when she quit her personnel job to look for work as a graphic artist. Her husband, a guidance counselor, ''made enough to cover the basic day-to-day living expenses'' that go with a house and family of four, Mrs. Webb recalls. But they still had to dip into savings to pay winter fuel bills and take out a loan so she could enroll in a nearby career center. Extras, like music lessons for their two sons, were put on hold until she began free-lancing.

It was no financial catastrophe, but ''it would have helped to really plan (better) ahead of time,'' she says.

Nearly 59 percent of all families headed by a married couple in the United States have two or more wage earners, according to the Bureau of Labor Statistics. And between job switching, layoffs, and child-rearing, it's quite likely that at some point, one of those earners will not be working for a time. Couples who have been through this experience, as well as financial planners, say it's a good idea to make provisions for this early on.

Bill Carter, president of Financial Planning Services in Dallas, calls it ''a necessity'' to plan for one income. ''When you get these two-income families - if they've planned well - they can do pretty much what they want to'' when there's just one earner, he says.

What is good planning? One financial adviser says it means saving the equivalent of three to seven months of living expenses. If it's a matter of figuring out when to quit, ''most people are not going to assume large expenses and then change careers,'' says John Cahill, of Carrol/Cahill Associates, a San Francisco financial planning outfit. One reason the Webbs' situation was not too cramping, says Mrs. Webb, was that they did get some major purchases out of the way before she quit and decided not to make any while she was unemployed.

It should be possible for a family to prepare for a temporary income slack in 12 to 18 months, figures Mr. Carter, although it all depends on how much has already been accumulated. He does not recommend taking out a personal loan to cover the time period, unless the entire loan can be paid back easily from income of the one earner. And a family that sees a layoff coming should begin ''saving aggressively'' and reworking its portfolio, moving assets out of timebound investments into something more liquid, like mutual funds or money market funds.

Don't forget that if you are laid off, unemployment compensation can ease the strain, too. Seven months of unemployment compensation ''made it possible to continue child day care part time while I looked for work,'' says Naomi M. Preheim, another Lexington resident, who was laid off and out of work for a year and a half. Ms. Preheim explains that her husband's salary was rising rapidly at the time and that ''we have bounced back rather easily.'' The spending cutbacks affected things like dining out, clothes shopping, and being able to hire a baby sitter. She says the family went ''into the hole'' for one of its vacations.

But the experience did teach her something. For one thing, she now sees their family finances more seriously. ''I was always conservative and thought that we needed a reserve in case something like the furnace blew,'' says Ms. Preheim, who is a business financial planner. ''Now I view it differently. I see (the reserve) as directly related to our jobs.'' Now, she would like to keep $4,000 liquid and $6,000 somewhat less accessible but not completely illiquid. Even though the family has two incomes again and increasing salaries, costs are rising too, especially as the family begins to plan for retirement and college for two children.