A.R.S. § 25-320 — Child Support and the Arizona Guidelines

How the statute works

The statute makes guideline support the presumptive order: the court applies the Arizona Child Support Guidelines unless their application would be inappropriate or unjust in the particular case, and any deviation requires written findings. The guidelines use an income shares model — both parents’ gross incomes combined set the total obligation, divided proportionally, then adjusted for parenting-time days, medical insurance premiums, and childcare costs.

Income, attribution, and disputes

Gross income is read broadly — wages, self-employment income, bonuses, rental income, recurring gifts. When a parent is voluntarily unemployed or underemployed, the court can attribute income at their earning capacity and calculate support on it. In practice, the contested cases are income cases: what a self-employed parent really earns, whether a career change was in good faith, and what the records actually show.

Retroactive support, duration, and modification

Support can be ordered back to the filing date — and where no order existed, the statute permits retroactive support for up to three years before filing, so waiting does not erase the obligation. Support runs until eighteen, or high-school graduation up to nineteen, with continued support available for a disabled adult child. Orders are modifiable on a substantial and continuing change of circumstances; the mechanics, enforcement tools, and the fifteen-percent rule are covered on our child support page.