What Every Parent Should Know
Arizona Follows Official, Court-Approved Guidelines
Arizona calculates child support under the Arizona Child Support Guidelines, adopted by the Arizona Supreme Court. Judges don’t simply estimate what seems fair — they follow a standardized worksheet that applies the same methodology to every case across the state.
This structure matters. It means the process is transparent and, to a meaningful degree, predictable.
The Four Key Factors That Shape the Final Number
1. Each Parent’s Gross Monthly Income: The court starts by examining both parents’ gross monthly income — that’s income before taxes. This can include:
- Salary and wages
- Bonuses and commissions
- Self-employment earnings
- Certain benefits and investment income
One important note: if a parent appears to be intentionally unemployed or working below their actual earning capacity, the court may assign income based on what that parent could reasonably earn. Voluntarily leaving a job typically does not reduce a support obligation.
2. Combined Income, the Basic Support Obligation, and Each Parent’s Proportional Share: Both incomes are added together and matched against a schedule within the Guidelines. That schedule sets a baseline child support amount based on:
- The parents’ combined monthly income
The number of children involved
Once the baseline is established, the court calculates each parent’s proportional share — that is, what percentage of the combined income each parent contributes. Here’s a straightforward example of how that works:
Hypothetically, if Parent A earns $4,000 per month and Parent B earns $6,000 per month, their combined income is $10,000. Parent A contributes 40% of that total; Parent B contributes 60%. If the Guidelines set the baseline support obligation at $1,500 per month for one child, Parent A’s share would be $600 and Parent B’s share would be $900.
3. Parenting Time: Arizona law refers to custody arrangements using two distinct terms:
- Legal decision-making — who makes major decisions about the child’s education, healthcare, and religion
- Parenting time — the actual schedule of overnights each parent has with the child
Parenting time directly affects the support calculation. When a parent has more overnights, they are assumed to be covering more day-to-day expenses directly — and the formula adjusts accordingly.
4. Additional Expenses: Beyond the baseline, the court factors in shared costs such as:
- Health insurance premiums for the child(ren)
- Work-related childcare expenses
- Private education costs, if any
- Certain extraordinary expenses (such as special education or medical needs)
When these costs are regular, recurring expenses, then the costs are included in the child support worksheet, divided between parents in proportion to their respective incomes, and will directly affect the final child support figure.
Other expenses that are less regular (e.g. medical co-pays, extracurricular activity fees), will be addressed outside of the monthly child support figure.
What Happens If Circumstances Change?
Child support orders are not permanent. Either parent can request a modification if there has been a substantial and continuing change in circumstances — for example, a significant shift in income, a job loss, or a meaningful change in the parenting time schedule.
Arizona courts take these requests seriously, but the change must be meaningful and ongoing — not temporary or minor.
Why the Details Matter More Than You Might Think
Arizona’s child support system is formula-driven and built for consistency. That said, seemingly small variables — how income is categorized, how overnights are counted, how expenses are allocated — can meaningfully shift the final number in either direction.
Understanding how the calculation works puts you in a stronger position to plan ahead, advocate for your child’s needs, and approach negotiations with clarity rather than uncertainty.
If you’re navigating a child support matter in Pima County, Arizona, speaking with an attorney at Rolfe Family Law can help you understand how these factors apply to your specific situation.