I think that @Taxing Matters hit it right on the head (from my reading of the statute).

It also works when you "Voluntarily Underemploy" yourself and take a job that pays significantly less than what you were making before for the purpose of paying less child support.

Same scenario, but Art takes a job as a checkout clerk at a local grocery store making $12,000 (from his ability to make $60,000) just so that the does not have to pay Becky the entire amount of Child Support. It seems that New Hampshire law will allow the system to ding Denise the remaining $48,000 to make up for the loss of income of Art.