If I, as a member of the paid workforce back in the day, had returned to work when our children were younger and in need of full-time child care, and our only concern was the difference between the cost of child care and the price of my labor (salary), I would have have needed to earn far more than I was earning at the time. What I was earning was nothing to sneeze at; I say this not because I’m greedy and wanted to keep a lot of my take-home pay, and not even because the price I put on being home with my children is so high (though it is).

It’s because of taxes–an issue devastatingly absent in all the back and forth among the Leaners In and Leaners Back and even among the Lean Forwards (I’m talking to you, political progressives).

An oped in today’s New York Times by Lilian V. Faulhaber of Boston University articulates the problem nicely, and asks some key questions: namely, Lean In? What About Child Care? In her two-differently-earning-mom scenarios, I’m closer to the second one:

Say she lives in New York State, where the average cost of day care for an infant is just over $14,000… The second woman’s husband makes $90,000, and the job she is considering pays $45,000… If she were single and without children, her after-tax take-home income would have been around $36,000. But because of her husband’s earnings, almost all of her income will now be taxed at a higher rate, 25 percent. After paying for child care, she will take home only around $16,000. This is not even factoring in the fact that many higher-paying jobs, just the type Ms. Sandberg wants women to lean in to, require longer hours — and the more expensive child care that entails.

It only makes economic sense to stay home with the kids (aside from the tremendous emotional sense it makes for me). But there’s a significant compromise, an outright cost, that comes with this sensible choice:

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.

Assuming (knocking on wood) that my husband and I remain together, and healthy, and financially stable, I should be able to avoid an even longer-term cost: a higher rate of poverty among aging women. (If you earn less on the dollar now, you’ll have less on the dollar later…)

“It’s the most important thing you can be doing right now,” so many, many well-intentioned friends and colleagues and strangers (yes, strangers) remind me when I say I’m home raising the children.

“Important” does not equal “valued.” It just doesn’t. Maybe there’s more value to somebody like me staying home:

• less congestion during workday commutes thanks to one fewer car?
• two less children taking up valuable space in our nation’s barely adequate number of affordable, flexible, high quality child care settings?
• less competition in the workplace because I am not there? (Just think of how many people could be given jobs if an extroverted, whip-smart, charismatic and efficient woman were not in the way? I’d guess at least two. Ha.)

Maybe. Maybe that’s why I have doubts that we’ll see any of what Professor Faulhaber suggests to remedy the situation, such as subsidized child care for all, or change the tax treatment of child care, whether as an increased credit or business deduction.

I lack no confidence, Ms. Sandberg, in case you (and other readers out there) were wondering. I do, however, lack faith that anybody in Congress, or that a majority voting for those in Congress, will put their money where their mouth is when they say,

“I value families.”

At least not in the next 15  years. Maybe by the time our daughter and son hit the paid workforce, they’ll shake their heads at how unfair and hypocritical we all once were.