Calculation is client-side, income figures are never transmitted or stored.
How Arizona Child Support Is Calculated
- Determine each parent's Child Support Income (gross income from all sources).
- Combine both parents' Adjusted Child Support Income to get Combined Adjusted Child Support Income.
- Look up the Basic Child Support Obligation from the official Schedule of Basic Support Obligations for that combined income and number of children.
- Each parent's proportionate share equals their income divided by the combined income, applied to the Combined Child Support Obligation.
- Apply the Parenting Time Table adjustment: the number of parenting-time days for the paying parent maps to an adjustment percentage (0% at 0-19 days up to 50% at 164+ days), multiplied by the Basic Child Support Obligation and subtracted from that parent's share.
- Apply the Self-Support Reserve Test: if the result would leave the paying parent below $1,685/month, the court may reduce the order.
Arizona Child Support Worksheet Walkthrough
Example: combined income $8,000/month, 2 children, Parent A earns $5,000/mo (62.5% share) and has 110 parenting-time days/year, Parent B earns $3,000/mo (37.5% share).
- Basic Child Support Obligation for $8,000 combined, 2 children: $1,622/month.
- Parent A's proportionate share: 62.5% × $1,622 = $1,014.
- 110 days falls in the 100-114 day bracket → 17.5% adjustment: $1,622 × 0.175 = $284.
- $1,014 − $284 = $730/month guideline child support paid by Parent A.
How This Calculator Works — Formula & Constants
Source: Arizona Child Support Guidelines (Arizona Supreme Court) · Calcul déterministe — no AI, no arbitrary estimate.
Constants used
| Constant | Value | Source |
|---|---|---|
| Self-support reserve | $1,685/mo | A.R.S. § 25-320 |
| Custody adjustment | Parenting Time Table (step function by day-range) | A.R.S. § 25-320 |
Formula
base_obligation = schedule_lookup(combined_income, children)
share_B = parentB_income / combined_income
total_obligation = base_obligation + childcare_cost + health_insurance_cost
obligation_B = total_obligation × share_B
obligation_B = obligation_B × (1 - custody_credit(overnights))
Deterministic calculation based on Arizona's official guideline schedule table. Verify against Arizona's official calculator for a court-ready figure.
FAQ
How is child support calculated in Arizona?
Determine each parent's Child Support Income (gross income from all sources). Combine both parents' Adjusted Child Support Income to get Combined Adjusted Child Support Income. Look up the Basic Child Support Obligation from the official Schedule of Basic Support Obligations for that combined income and number of children. Each parent's proportionate share equals their income divided by the combined income, applied to the Combined Child Support Obligation. Apply the Parenting Time Table adjustment: the number of parenting-time days for the paying parent maps to an adjustment percentage (0% at 0-19 days up to 50% at 164+ days), multiplied by the Basic Child Support Obligation and subtracted from that parent's share. Apply the Self-Support Reserve Test: if the result would leave the paying parent below $1,685/month, the court may reduce the order.
How does Arizona's Parenting Time Table work?
See the guidelines section above.
What counts as Child Support Income in Arizona?
See the guidelines section above.
What happens if combined income is above $30,000/month?
See the guidelines section above.
Methodology & Source
Formula model: income shares. Effective 2022-01-01, guideline version 2022-AZ-v1, last reviewed 2026-07-11.
Official source: Arizona Child Support Guidelines (Arizona Supreme Court) (A.R.S. § 25-320).
Courts may deviate if combined income exceeds $30,000/month with significant income disparity, or for other documented reasons (Section IX) — this calculator shows the presumptive guideline amount only, not a court order. Note: at exactly equal (50/50) parenting time, Arizona's guidelines may still order the higher-earning parent to pay support based on income disparity alone — this calculator determines the paying parent from parenting-time majority and may not reflect that specific scenario; consult an attorney if your parenting time is exactly equal.
Guideline figures transcribed from the primary source above and cross-checked against Arizona's official calculator/worksheet for multiple test scenarios — see our verification methodology.