Arizona calculates child support using the Income Shares Model: the court adds both parents’ adjusted incomes together, finds a Basic Child Support Obligation on a state schedule, and splits that amount between the parents in proportion to what each one earns. From there the number gets adjusted for things like health insurance, childcare, and how much parenting time each parent has with the kids. The legal basis is A.R.S. § 25-320, and the math itself lives in the Arizona Child Support Guidelines.
You don’t have to do this by hand. The Arizona Supreme Court publishes an official calculator, and you can run your own numbers through our free child support calculator to get a working estimate before you sit down with the court forms. Any calculator result is an estimate — the court has the final authority to set the amount. What follows is a walk-through of how the formula actually works, step by step, so the number you get doesn’t feel like it came out of nowhere.
Which guidelines apply right now
Arizona updates its child support guidelines periodically, and it matters which version applies to your case. As of this writing, the guidelines in effect are the 2022 Arizona Child Support Guidelines, effective January 1, 2022, and revised September 21, 2022. They apply to child support orders and modifications entered after that date, with a few exceptions: if the court enters a default, or if the parties agree, or if the court finds good cause, the guidelines in effect when the case was filed can be used instead. The Arizona Supreme Court is required to review the guidelines at least once every four years under A.R.S. § 25-320(D), and the next review cycle is already underway, so check the guidelines page before you file in case a newer version has taken effect.
Step 1: Each parent’s income
The guidelines call this “Child Support Income,” and it’s broader than what shows up on a pay stub. It includes wages, salary, commissions, bonuses, self-employment earnings, military pay and allowances, pensions, interest and dividends, Social Security benefits, unemployment and disability benefits, recurring gifts, and spousal maintenance a parent receives — all counted before taxes or other deductions. It does not include means-tested benefits like TANF, SSI, or Nutrition Assistance, or child support a parent receives. A stepparent’s income is not counted either, because a stepparent has no legal duty to support the child.
If a parent is unemployed or underemployed, the court can attribute income to them, but it has to consider the reasons first — whether the situation is voluntary or involuntary — along with the child’s best interests and factors like work history, job skills, education, health, employment barriers, and the local job market. A.R.S. § 25-320(N) presumes a parent is capable of at least full-time work at the applicable state or federal adult minimum wage, whichever is higher, and the court usually treats full-time as 40 hours a week.
Step 2: Adjustments for spousal maintenance and other kids
Before the two incomes get combined, each one may be adjusted. If a parent is actually paying court-ordered spousal maintenance resulting from this marriage, that amount comes off their income, and it gets added to the income of the parent receiving it. Payments toward maintenance arrears don’t count. Because maintenance ordered after 2018 is no longer tax-deductible to the payer, the guidelines allow the adjustment to be “grossed up” to reflect the pre-tax income needed to fund the payment.
If a parent is actually paying court-ordered support for a child from a different relationship, that amount is also deducted — though the parent has to show the order is genuinely being paid. And if a parent is the primary residential parent of a child from another relationship who isn’t part of this case, their income gets reduced using a simplified application of the guidelines schedule. These adjustments exist so the formula doesn’t ignore the fact that a parent may already have other legal support obligations.
Step 3: The Basic Child Support Obligation
Once both incomes are adjusted, they’re added together into a single number: Combined Adjusted Child Support Income. That number gets located on the state’s Schedule of Basic Support Obligations, cross-referenced against the number of children involved, to produce the Basic Child Support Obligation. The schedule runs from a combined income of $750 up to $30,000 a month. If combined income exceeds $30,000 and neither parent asks the court to consider more, the figure at $30,000 is used; if a parent does ask, the court decides whether a higher amount is in the child’s best interests based on the evidence.
From there, the obligation is adjusted upward by 10% for children age 12 and older, since the guidelines assume older kids cost more. If only some of the children on the order are 12 or over, that 10% increase is prorated to their share of the obligation rather than applied to the whole thing.
Step 4: Add-on costs
The basic schedule assumes a household living together, so it doesn’t account for costs specific to split households. The guidelines add in the child’s medical insurance premium (or the portion attributable to the child, prorated if the policy covers other people too), childcare expenses a parent incurs in order to work or look for work, and in some cases reasonable education or extraordinary child expenses. These get added to the Basic Child Support Obligation to produce the Combined Child Support Obligation, which is then split between the parents in proportion to their share of the combined income.
Run your own numbers
Once you know both parents’ approximate monthly incomes and the parenting-time split, our free child support calculator will walk you through the same steps the court uses, so you have an estimate to check against the official worksheet before you file anything.
Step 5: The parenting-time adjustment
This is where a lot of self-represented parents get tripped up. Arizona’s guidelines include a Parenting Time Table that reduces the obligation of the parent with less parenting time, based on how many parenting-time days that parent has with the child each year. Arizona does not count overnights. It counts blocks of time, measured from one exchange to the next: one day for every 24 hours in the block, and then, for whatever is left over, 12 hours or more counts as a full day, 6 to 11 hours as a half day, and 3 to 5 hours as a quarter day. A period under 3 hours may count as a quarter day if that parent covers routine costs like meals during it.
The total annual days are matched to a range on the table, and each range corresponds to an adjustment percentage that’s multiplied by the Basic Child Support Obligation and subtracted from that parent’s proportionate share. At 0 to 19 days, there’s no adjustment. The percentages step up through the ranges, and at 164 days or more the adjustment reaches its maximum of 50%. Even with essentially equal parenting time, a parent can still owe support if their adjusted income is higher than the other parent’s, or if the children’s expenses aren’t shared equally — the formula weighs income share and parenting time together.
Step 6: The self-support reserve test
Before finalizing a support order for a lower-income paying parent, the guidelines apply a Self-Support Reserve Test to check that the paying parent can meet the order and still maintain a minimum standard of living. The reserve is 80% of the monthly full-time earnings at the state minimum wage for the year support is being calculated. If subtracting the reserve from the paying parent’s adjusted income leaves less than the calculated support amount, the court may reduce the order — but before it does, it has to run the same test on the receiving parent and weigh the financial impact a reduction would have on that household. Because Arizona’s minimum wage is adjusted annually, the dollar figure changes from year to year; the calculator applies whatever figure is current when you run it.
When can a judge deviate from the formula?
The number the formula produces is presumed correct. A judge orders a different amount — a deviation — only after finding that applying the guidelines would be inappropriate or unjust in that specific case and after considering the child’s best interests. Those findings have to be in writing, in the child support order, minute entry, or worksheet, and the judge also has to show what the order would have been without the deviation and what it is after deviating. Notably, the guidelines say a deviation that lowers support is not, by itself, contrary to the child’s best interests.
Parents can jointly request a deviation too, but only if the agreement is in writing or stated on the record under Rule 69 of the Arizona Rules of Family Law Procedure, both parents knew what the guideline amount would have been before agreeing to something different, and the agreement was made free of duress and coercion. Rounding the final number for ease of accounting, compromising on an individual input like a parenting-time figure, or reducing an order under the self-support reserve test is not considered a deviation.
How to actually file
Arizona courts use a Parent’s Worksheet for Child Support to document the calculation, and it gets attached to the court order. You can generate the worksheet and related documents through ezCourtForms, the interview-driven calculator offered for statewide use through the Superior Court in Maricopa County, or prepare and e-file your paperwork through AZTurboCourt. Most county superior courts also have a self-service center that can help you locate the right forms and walk through the filing process in person. If you want a state agency to establish, calculate, or enforce a support order for you — including cases involving public assistance — the Arizona Department of Economic Security’s Division of Child Support Services (DCSS) handles Title IV-D cases and has its own application process. If you’re building your case yourself and want a step-by-step reference to keep next to your worksheet, the book Navigating Child Support walks through the paperwork side of a self-represented case in more detail.
Frequently asked questions
Does Arizona use a flat percentage of income like some states?
No. Arizona uses the Income Shares Model, which starts with both parents’ combined income and a state schedule, rather than applying a fixed percentage to one parent’s income alone.
Does 50/50 parenting time mean neither parent pays support?
Not automatically. Even with equal or close-to-equal parenting time, a parent with higher adjusted income can still owe support, because the formula weighs both income share and parenting time. Support can also be owed when the children’s expenses aren’t shared equally.
What counts as income if a parent is self-employed?
For self-employment, rent, royalties, or a closely held business, the guidelines use gross receipts minus the ordinary and necessary expenses the court finds were required to produce the income. Those expenses include one-half of the self-employment tax actually paid.
Can parents agree to a different amount than the calculator produces?
Yes, but the court still has to approve it. The agreement must be in writing or stated on the record under Rule 69, entered free of duress and coercion, and made with both parents knowing what the guideline amount would otherwise have been.
Where do I get the official worksheet to file with the court?
The Parent’s Worksheet for Child Support can be generated through ezCourtForms or filed through AZTurboCourt, and your county’s self-service center can help you complete and file it correctly.
Sources and citations
- A.R.S. § 25-320, Child support; factors; methods of payment — azleg.gov
- Arizona Child Support Guidelines, effective January 1, 2022 (revised September 21, 2022); adopted by Administrative Order 2021-56 and revised by AO 2021-131, AO 2021-149, and AO 2022-116 — azcourts.gov
- About the Child Support Calculator — azcourts.gov
- AZTurboCourt e-filing information — azcourts.gov
- Arizona Child Support Calculator overview — azcourthelp.org
- Division of Child Support Services (DCSS) — des.az.gov
This article is educational information about how Arizona’s child support formula generally works. It is not legal advice, and it does not account for the facts of your specific case. Guidelines, statutes, dollar thresholds, and forms change over time. For guidance on your situation, consult a licensed Arizona family law attorney or your county Superior Court self-help resources.
