How is Child Support Calculated in Arizona?

Arizona calculates child support using the Income Shares Model under A.R.S. § 25-320. The process starts with both parents' gross incomes, applies specific adjustments to produce an Adjusted Child Support Income for each parent, combines those figures, and then looks up the basic obligation on the state's schedule. Each parent pays their proportional share based on their percentage of combined adjusted income.

Arizona uses neither raw gross income nor net income after taxes. It uses adjusted gross income — gross income minus a specific set of deductions. Understanding what those deductions are is important, because they can meaningfully change the income figures that flow into the calculation.

Step One: Calculate Adjusted Child Support Income

Arizona's guidelines start with each parent's gross monthly income — all income from all sources before taxes. From that gross income, three specific deductions produce the Adjusted Child Support Income (ACSI) for each parent:

Deduction 1 — Prior court-ordered child support. If a parent is already paying child support for children from another relationship under a court order, that amount is subtracted from gross income.

Deduction 2 — Court-ordered spousal maintenance paid to a former spouse. If a parent is currently paying alimony or spousal maintenance to an ex-spouse from a prior marriage, that amount is subtracted from gross income.

Deduction 3 — The parent's own health insurance premium. The portion of the parent's health insurance premium that covers only the parent themselves — not the child — is subtracted from gross income. The child's portion of the premium is handled separately as an add-on expense, not a deduction.

After these three deductions, the result is each parent's Adjusted Child Support Income — the number that flows into the schedule.

Step Two: Look Up the Basic Child Support Obligation

Both parents' Adjusted Child Support Incomes are combined into a single Combined Adjusted Child Support Income (CACSI). That figure is matched against Arizona's Schedule of Basic Support Obligations — a table covering combined adjusted monthly incomes from $1,000 to $30,000 and family sizes from one to six children.

The schedule produces the basic child support obligation — the baseline amount covering the child's core needs including food, clothing, shelter, transportation, and routine medical care. It doesn't cover health insurance premiums, childcare, or extraordinary expenses — those are calculated separately and added on top.

Approximate figures based on the Arizona Child Support Guidelines Schedule. Actual amounts depend on the precise income level and the schedule in effect at the time of the order.

Step Three: Divide the Obligation Between Parents

Each parent's share of the basic obligation is calculated by dividing their individual ACSI by the combined ACSI. That percentage is their proportional share of the total support amount.

In a sole-custody arrangement — one parent has primary physical custody — the non-primary parent makes a direct monthly payment of their proportional share to the primary parent. The primary parent's share is presumed spent directly on the child during their time.

The Parenting Time Adjustment

Arizona provides a parenting time credit that reduces the non-primary parent's obligation based on the number of days per year they spend with the child. The more time a parent has with the child, the more direct costs they bear — and the adjustment accounts for that.

The credit is applied using a parenting time table that matches the number of annual days to a percentage reduction in the basic obligation. The adjustment is applied after the basic obligation is calculated. In true shared parenting arrangements — where each parent has the child roughly half the time — the credit can substantially reduce or eliminate the net transfer payment between parents, especially when their incomes are similar.

Add-Ons: Health Insurance and Childcare

Three categories of expenses are added on top of the basic obligation and split proportionally between parents based on their ACSI percentages:

The child's health insurance premium: The portion of the premium attributable to the child (total premium minus the parent's own coverage) is divided proportionally. Courts designate which parent carries the child on their policy and which reimburses their share.

Work-related childcare costs: Childcare expenses necessary for a parent to work or attend education or training are split proportionally. Arizona allows a 25% reduction to reflect the federal child and dependent care tax credit before splitting the cost.

Extraordinary medical expenses: Unreimbursed medical costs above a defined threshold are split proportionally. Routine co-pays and prescriptions are typically covered by the base obligation and not added separately.

Income Imputation: The Minimum Wage Floor

Arizona courts presume that a parent who is voluntarily unemployed or underemployed is capable of earning at least minimum wage. Arizona's minimum wage in 2026 is $15.15 per hour — approximately $2,626/month at full-time hours. If a parent has no income and no legitimate reason for unemployment, courts may impute this minimum wage income into the calculation rather than accepting zero.

Courts can impute higher income based on a parent's education, work history, and the local job market. The imputation standard is what the parent is reasonably capable of earning — not what they are currently earning if they are voluntarily reducing their income.

Above the $30,000 Cap

When combined adjusted monthly income exceeds $30,000, the Arizona schedule no longer provides a direct figure. Courts apply discretion — starting from the obligation at $30,000 and considering the child's actual needs, each parent's lifestyle, and the standard of living during the marriage. Above the cap, child support becomes more individualized and less formula-driven.

When Does Child Support End in Arizona?

Arizona child support generally ends when the child turns 18 or graduates from high school — whichever is later — but not past age 19. A child who turns 18 mid-school-year continues receiving support through graduation, up to the 19-year cap.

If the child has a physical or mental disability preventing self-sufficiency, courts may order support beyond 19. Arizona doesn't generally require parents to contribute to college expenses through the child support order — unlike New Jersey. College cost agreements, if negotiated, typically go into the separation agreement rather than the guidelines order.