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?
Arizona's Parenting Time Table maps the paying parent's annual parenting-time days directly to an adjustment percentage — 0% at 0-19 days, rising in steps up to 50% at 164 or more days per year. That percentage is multiplied by the Basic Child Support Obligation and subtracted from the paying parent's proportionate share, so more parenting time directly lowers the guideline amount.
What counts as Child Support Income in Arizona?
Child Support Income in Arizona is gross income from all sources — wages, self-employment, bonuses, and other resources — before taxes, not net take-home pay. Both parents' Child Support Income is combined to look up the Basic Child Support Obligation on the official schedule.
What happens if combined income is above $30,000/month?
The official Arizona schedule of Basic Support Obligations is built out through $30,000/month in combined Child Support Income. Above that ceiling, the schedule doesn't provide a table value, so courts use discretion to set an appropriate amount rather than an automatic formula extension.
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.
Related Tools
- Joint Custody Child Support Calculator — how shared parenting time changes this calculation
- Military Child Support Calculator — BAH/BAS and other military pay as income