Probably the most overlooked aspect of arranging child care is arranging the finances, says Kim Smith, coauthor of The Metropolitan Mothers at Work Book. That is especially surprising, she adds, when you consider the hefty price tag on most child-care options.

In the Washington metropolitan area, for instance, the cost of infant care outside the home can be prohibitive, typically from $100 and up a week, not including transportation. Live-in care and day care in your home are more expensive.

Parents budgeting child care into their living expenses often ignore a variety of financial assistance possibilities. "The programs are available, and they're out there," says Smith. "It's very important in any child-care center or facility to ask what kind of financial assistance programs are available. Some have scholarships, some work with head-start programs. Some work with aid to families with dependent children programs . . .

"For example, there are 19 different D.C. day-care recreation programs, with fees ranging from zero dollars to $2.60 per day, dependent on family size and parents' gross income. That's cheap. If the child is handicapped, the care is free. To be eligible, the mother has just got to be working 15 hours a week."

Despite budget slashing by the Reagan administration of government-sponsored day-care assistance programs, "some are still in existence," says Smith. "Whenever you contact a center, ask what programs are available and don't get into saying, 'I make a lot of money and there won't be anything available for me.' That's not always the case. In Prince George's County, if you spend over 10 percent of your income for child care, you are entitled to a subsidy. That means you can be making $50,000 a year, and if you spend $5,000 on child care, you get assistance.

"There are all sorts of strange and wonderful things out there. You've just got to ask." Among the financial assistance parents should know about:

The largest single source of financial relief comes from the child-care tax credit for working parents in the federal tax code. Maryland, Virginia and the District also offer child-care tax benefits.

Employer-assisted child care "is getting to be the employe benefit of the '80s," says Smith, citing a Harris poll in which more than two-thirds of employers nationwide said they expected to be providing some form of child-care services to employes within five years.

"Far-sighted employers are already doing this," says Smith. "Whether they put child-care facilities on site or provide vouchers that help parents pay for child care, studies show that it results in improved morale, increased production, a decline in absenteeism, lower turnover and easier recruitment."

Help for low-income families comes in many forms, many of which are hard to find in the bureaucratic maze, says Smith. Head Start, for instance, has proven to be an effective program, graduating 9 million in its 21-year history. And local Title XX programs help provide subsidized day-care centers.

Recognition by state and local governments of the increased need for before- and after-school care has resulted in funding for such programs, as well as some prekindergarten programs, in local school districts.

For further information about financial assistance and referral agencies, Smith recommends calling the Childcare Network Information Line, 223-0050, a recorded listing sponsored by the Metropolitan Council of Governments.