The wife bonus.
It's a year-end check from the husband that's based on her performance. How well the house, or houses, were managed and whether the kids were successful at school, for example.
Wednesday Martin, anthropologist, author and mommy blogger, moved with her husband and two sons to New York City's Upper East Side to be near Central Park, her in-laws and better schools.
But what she found at the playgrounds and nursery schools were educated women married to rich and powerful men who ran their family life like a CEO and were rewarded in much the same way.
Her recent essay in the New York Times, which described the "wife bonuses," was the opening volley in yet another skirmish in the Mommy Wars.
Were these women, who "exercised themselves to a razor's edge" and "exhaustively enrich[ed] their children's lives by virtually every measure," powerless and dependent on their husband's wealth?
Or were they the other half of a team of equals managing — and financing — a pretty complex lifestyle?
Ms. Martin makes a good case for herself as a neutral observer of how unusual societies arrange themselves, "from the Amazon basin to sororities at a Big Ten school." She said she wasn't judging, but when she arrived on the Upper East Side, "my culture shock was immediate and comprehensive."
But those who joined the lively online discussion that followed the publication of her essay called her a reverse snob and accused her of assuming that wealthy marriages are necessarily shallow and transactional.
Ms. Martin, who has written a book about her six-year study of more than 100 of these women titled "Primates of Park Avenue," described them as 30-somethings with advanced degrees from prestigious universities and business schools.
Their husbands were often investment bankers or hedge fund managers, and they had three or four kids under 10. They mostly gave away their education and their skills by volunteering to organize galas, run libraries or edit newsletters.
She said they themselves described their world as "weird."
Those who joined the conversation alternately accused these women of hiring people to raise their children for them and of being devoted mothers whose children benefited from having their full attention.
Some said that these women were demonstrating the same freedom of choice that men have. Others said the women were nothing but contractual domestic workers, in constant danger of being traded for a newer model.
But it was the "wife bonuses" that caused the biggest stir. Even the women themselves, Ms. Martin wrote, would become reticent when she pressed for details. But they regularly mentioned that they would be making a major purchase or a major contribution to charity as soon as they knew the amount of these bonuses.
It wasn't clear whether the bonus was based on how he was prospering at work or how successful she was at getting the kids into a fancy private school. Was the money her share of the family income? Or was it strictly linked to how things were going at home?
It wasn't clear who decides if she gets the bonus. What happens in the bedroom if he passes her over? And how do you put a price tag on the fact the kid made a travel soccer team or the fact that she hasn't run through four nannies every quarter?
At roughly the same time Ms. Martin's essay appeared, there was a news report on working mothers that seemed to suggest that these glamorous stay at home moms need to get a job if they want their children, especially daughters, to succeed in life.
Research shows that daughters of working mothers completed more years of education, were more likely to be employed in supervisory roles and earned higher incomes.
"Part of this working mother's guilt has been, 'Oh my kids are going to be so much better off if I stay home,'" Kathleen McGinn, Harvard Business School professor and an author of the study told the New York Times. But she found the kids were much better off as adults if she worked.
It didn't necessarily influence the careers of sons — they are generally expected to work, the report said. But sons of working mothers spend more time on child care and housework in their own families.
Unless they run a hedge fund, I guess.
Susan Reimer's column appears on Mondays and Thursdays. She can be reached at firstname.lastname@example.org and @SusanReimer on Twitter.com.