How Arizona calculates child support

Both parents' incomes are combined. The state's published Schedule of Basic Support Obligations tells you what families at that combined income level typically spend on children each month. That basic obligation is split between the parents in proportion to their incomes — a parent who earns 60% of the combined income owes 60% of the obligation. From there, parenting time, health insurance, childcare, and a handful of other adjustments shift the final amount up or down. The result is a presumed amount that courts apply unless someone proves a deviation is appropriate.

Arizona uses the Income Shares Model, which is the most common approach in the United States. It assumes children should receive the same proportion of their parents' incomes as they would have if the parents lived in one household.

Arizona updated its child support guidelines effective January 1, 2022. The previous version was from 2018. If you're reading older articles or have an older child support order, the math may have changed. Key changes in 2022:

• The Schedule of Basic Support Obligations was updated based on more recent economic research on what raising children actually costs in Arizona. Most amounts went up.
• The income cap on the schedule was raised from $20,000 to $30,000 per month combined. Above $30,000, the court decides what is in the child's best interests rather than applying the schedule.
• “Gross income” was renamed “Child Support Income.” The substance is similar, but the new term reduces confusion with tax-related definitions of gross income.
• The older child adjustment (10% for children 12+) became mandatory. Previously it was discretionary.
• A clearer self-support reserve test protects low-income paying parents from orders that would push them below subsistence.
• The structure was reorganized to follow the same sequence as the official Child Support Worksheet, making it easier to follow step by step.

These guidelines are reviewed every four years under federal law, so the next significant update is expected in 2026.

Child Support Income is broader than what shows up on a W-2. It includes wages, salaries, commissions, bonuses, tips, self-employment income (gross receipts minus ordinary and necessary business expenses), rental and royalty income, pensions, annuities, Social Security benefits, spousal maintenance received from a non-party, workers' compensation, disability and unemployment benefits, and the cash value of significant in-kind benefits like employer-provided housing or a company car.

It does not include means-tested public assistance (TANF, SSI, food stamps), child support received for other children, or survivor benefits paid for the children at issue.

If a parent is voluntarily unemployed or underemployed, courts can impute income based on what the parent could earn. Arizona presumes every parent can work full-time at minimum wage, so courts may impute at least that amount even when actual income is zero.

Each parent's Child Support Income is reduced by certain adjustments, including court-ordered child support being paid for other children, spousal maintenance being paid to a former spouse, and support actually being paid for prior-born children even without a court order in some cases.

Spousal maintenance creates a double-entry: the paying parent deducts it from their income, and the receiving parent adds it to theirs. The net effect shifts the income calculation toward the actual financial reality after maintenance.

Both parents' Adjusted Child Support Incomes are added together to get the Combined Adjusted Child Support Income. That figure is used to look up the Basic Child Support Obligation from the Schedule of Basic Support Obligations — a published table that maps combined income to a monthly basic obligation, with separate columns for one through six children.

The schedule covers combined income from $0 up to $30,000/month. Above $30,000/month, the court determines what amount is in the child's best interests. There is no formulaic answer above the cap.

Several costs are added to the basic obligation before the parents' shares are calculated:

• Health insurance for the children — only the portion of the premium attributable to the children, not the whole family plan
• Work-related childcare costs — daycare, after-school care, and similar
• Extraordinary education or healthcare costs for the child
• The older child adjustment — for any child 12 or older, the basic obligation is increased by 10%. If some children are 12+ and others are not, the adjustment is prorated.

The total of the basic obligation plus these additions is the Combined Child Support Obligation.

Each parent's share of the Combined Child Support Obligation equals their share of the Combined Adjusted Child Support Income. If Parent A has $6,000/month adjusted income and Parent B has $4,000/month, the combined is $10,000. Parent A's share is 60% and Parent B's is 40%. The obligation is split accordingly.

The parent with less parenting time gets a credit based on how many days per year they have the children. Arizona uses a Parenting Time Table that maps days to a percentage adjustment.

The math is more nuanced than “50/50 means no support.” Even with equal parenting time, if one parent earns substantially more, that parent typically still owes support. The parenting time table captures the reality that some expenses are duplicated between households while others are controlled by one parent regardless.

Arizona measures parenting time in 24-hour blocks (days), not just overnights. Equal parenting time is approximately 164 days per parent per year — not 182.5 — because of how the Parenting Time Table is constructed.

If the calculated support amount would push the paying parent below the Self-Support Reserve ($1,685/month) — equal to 80% of full-time minimum wage — the court can reduce the support to keep the paying parent above subsistence. The court considers the financial impact on the receiving parent's household before applying this reduction.

The result of all eight steps is the Presumptive Child Support Amount. This is what courts apply unless someone proves a deviation is appropriate.

Arizona child support generally ends on the last day of the month in which the child turns 18, with three exceptions:

1. High school still in progress at 18. Support continues until the child graduates from high school or turns 19, whichever comes first.
2. Severely disabled children. Under A.R.S. § 25-320(E), courts may order support to continue past the age of majority for children with severe mental or physical disabilities who cannot live independently. There is no automatic age cutoff in these cases.
3. Agreed college support. Parents can voluntarily agree to extend support, and the court can incorporate that into the order. This is not automatic — it requires explicit agreement.

For most cases, support ends at high school graduation, typically a few months after the child's 18th birthday.

The calculator implements the Schedule of Basic Support Obligations and the Parenting Time Table from the 2022 guidelines. It does not account for:

• Deviations from the guideline amount. Courts can order more or less than the guideline figure if the guideline result is “inappropriate or unjust.” The calculator gives the presumptive amount; deviations are case-by-case judicial determinations.
• Imputed income. The calculator uses whatever income you enter. Whether a court would impute additional income to a parent is a fact-specific judgment no calculator can replicate.
• Extraordinary expenses like private school tuition, special-needs medical care, or significant travel costs.
• Combined income above $30,000/month. Above the schedule's cap, the court determines the amount.
• Complex self-employment income involving depreciation timing, retained earnings, or personal expenses run through a business.

For any of these situations, a family law attorney is the right starting point. This calculator is a starting point, not a final answer.

This guide and the calculator implement the 2022 Arizona Child Support Guidelines as adopted by the Arizona Supreme Court. Primary sources:

• Arizona Child Support Guidelines (full text, 2022) — Arizona Judicial Branch
• A.R.S. § 25-320 — the statute requiring child support and authorizing the guidelines
• A.R.S. § 25-501 — termination of support
• Schedule of Basic Support Obligations — published as part of the guidelines
• Parenting Time Table — published as part of the guidelines

For binding numbers, use the official calculator from the Arizona Judicial Branch. If you see a meaningful difference between this calculator and the official one, please report it.

Last verified: 2026-04-28