That decision has a long-term impact. Every year out of the office will affect these women’s retirement savings and Social Security contributions, their chances for promotion, and the likelihood that they will eventually be able to re-enter the work force at the same level and salary. This quite likely contributes to the relatively higher rates of female poverty, especially in old age.

The child and dependent care credit, created in 1976, was meant to address these skewed incentives. But the credit severely underestimates the cost of child care, and is phased out too quickly for higher-earning couples.

The most working parents can receive through the credit is $1,050 (or $2,100 for two or more children), but this amount decreases to $600 (or $1,200 for two or more children) as income increases. Even a couple making $50,000 could use it to reduce their taxes by only $600. Congress was right to prioritize the lowest-income parents, but it shouldn’t ignore the impact policies have on other groups.

What can be done? We could decrease tax rates over all, but that wouldn’t target the obstacles facing second-earners. There are three better possibilities.

We could directly address the high cost of child care by providing or subsidizing such care, as France and Sweden do. (Congress does allow employers to, in effect, subsidize their employees’ child care expenses by letting them exclude a portion from their income. But many companies, particularly smaller ones, do not offer this option, and those that do can exclude only up to $5,000.)

A different approach would be to focus on the tax treatment of child care. We could increase the child and dependent care credit to include the full cost (or at least a higher portion of the cost) of child care, which would increase parents’ after-tax income. Or we could treat child care as a business deduction. This would let parents pay for it out of their pretax income, and would have the added symbolic benefit of acknowledging that child care costs are ordinary and necessary business expenses.

It is unlikely that any of these proposals would pass in the face of sequestration. Nonetheless, we need to acknowledge that women (and other second-earners) are not opting out of the workplace without encouragement. If we truly want them to lean in to the work force, we need to have a tax system that does not push them out.