Jonathan Pond, a financial planner and author of "The New Century Family Money Book," has analyzed the cost advantages when both spouses work. He based his analysis on a Boston-area employee with an average annual income of $30,000. Here's what he found:
* Pretax income: $30,000.
* After federal, state and social security tax: $22,500 left.
* After child-care expenses of $180 a week: $14,000 (also takes into account $1,000 child-care tax credit).

