This is a mistake. They can agree on a percentage of his earnings that is small, and they can mutually agree to set date that child support begins to several years in advance, AND she can choose to never enforce, but it is a mistake to wave entirely. Children get exponentially more expensive as they age, and altruistic intentions as a young mother are not fair to heap upon your future teen who may end up with unforeseen issues, psychological, medical or otherwise. I myself had thought I would never want child-support, and at this point I am not going to do anything legally to enforce the rather paltry sum I did put into divorce agreement; but if someday I am bankrupt and my son is in need, you bet your sweet ass I will enforce that shit. It is easy to just want to be done with a person, but they have a responsibility to the child they mutually chose to create that has nothing to do with the other parent.