You’ve probably heard of the “mommy penalty.” Turns out there’s a “daddy bonus,” too—where fathers make more money than men without kids.

That’s right. In 2010, men without children earned 40% less than men who were fathers, according to a study by Justine Calcagno, a social psychologist and Ph. D candidate at the City University of New York’s Graduate Center. The study is based on personal income data in the Census Bureau’s American Community Survey.

A big driver here is that fathers skew older than child-less men. And older men have had more time to develop careers, change jobs, and increase pay. (In this study, men “with children,” by the way, are defined as those whose children live with them— so “child-less” men includes fathers whose kids have left the nest.)