How does a court weigh a payor's new spouse's income in an undue hardship application?

A new spouse's income becomes relevant at the second stage of an undue hardship analysis, where the court compares the standard of living in the payor's household against the recipient's household, because that comparison looks at the household as a whole rather than the payor's individual income alone. If a payor has remarried or moved in with a partner who earns a significant income, that household income is generally factored into the standard-of-living comparison, which can make it harder for the payor to show their household's standard of living is actually lower.

This can feel counterintuitive to a payor who feels the hardship is personal to them, but the Guidelines approach hardship at the household level specifically because that's what actually determines the resources realistically available for the child's benefit and the payor's own obligations. The new spouse is not personally required to support the payor's child, but their income still shapes the comparison used to assess whether the payor's household is genuinely worse off. Because this calculation can be counterintuitive and fact-sensitive, a payor considering an undue hardship claim involving a new relationship should get legal advice on how the comparison will likely play out before proceeding.