One of the dilemmas of social policy is the eligibility "cliff effect" --the point at higher earnings push a family beyond eligibility for means-tested benefits such as children's health insurance coverage, home energy assistance or eligibility for a low-income tax credits. Poorly-designed eligibility thresholds can actually cause dips in family resources, as a small increase in earnigns is offset by a sharp drop in benefits.  For examples, see National Center for Children in Poverty, Making Work Pay: Examining Work Supports in Iowa (2008), and the video below from the Indiana Institute for Working Families.