Child support orders aren't permanent. Life changes — jobs change, incomes rise or fall, children's needs evolve, and parenting time shifts. When those changes are significant enough, Arizona law allows either parent to request a modification. Here's exactly how the process works.
When Can You Modify Child Support?
Arizona allows modification of child support when there has been a "substantial and continuing" change in circumstances since the last order was entered. Under the Arizona Child Support Guidelines, the most straightforward trigger is the 15% rule: if running the current numbers through the Guidelines produces an amount that differs from the current order by 15% or more, the court will generally find that a modification is warranted.
Common Reasons for Modification
| Change in Circumstances | Typical Impact |
|---|---|
| Significant income increase (either parent) | Support may increase or decrease depending on who earns more |
| Job loss or involuntary income reduction | Support may decrease (voluntary underemployment is treated differently) |
| Change in parenting time | More time with one parent = potential adjustment |
| Change in child's needs (medical, educational) | Support may increase to cover new expenses |
| Child turning 18 or graduating high school | Support typically ends; adjustment needed for remaining children |
| New child from another relationship | May reduce available income, potentially lowering support |
| Change in health insurance costs | Insurance is factored into the Guidelines calculation |
| Remarriage of either parent | New spouse's income generally doesn't count, but may affect expenses |
The Arizona Child Support Guidelines
Unlike spousal maintenance, child support in Arizona follows a specific formula — the Arizona Child Support Guidelines. The calculation considers both parents' gross monthly income, the number of children, the parenting time schedule (how many days each parent has the children), health insurance premiums for the children, childcare costs related to employment or education, extraordinary expenses for the child (special education, chronic medical needs), and any child support obligations for children from other relationships.
The Arizona Supreme Court provides an online Child Support Calculator that both parents can use to estimate what the Guidelines would produce based on current numbers. This is a good first step to determine whether your current order is significantly out of line.
Step-by-Step: How to File for a Modification
Run the numbers
Use the Arizona Child Support Calculator with current income figures, parenting time, and expenses. If the result differs from your current order by 15% or more, you likely have grounds for modification.
Gather documentation
Collect recent pay stubs (at least 3 months), tax returns (most recent 2 years), proof of any changed expenses (childcare, health insurance, medical bills), and documentation of the changed circumstance (layoff letter, new parenting time order, etc.).
File a Petition to Modify
File a Petition to Modify Child Support with the Superior Court in the county that issued the original order. In Maricopa County, you can use the Self-Service Center forms. You'll need to pay a filing fee (typically around $250-$300).
Serve the other parent
The other parent must be formally notified of the petition, just like in a divorce filing. They'll have time to respond and submit their own financial information.
Attend a hearing or negotiate
If both parents agree on the new amount, you can submit a stipulated agreement for the judge to approve. If not, the court will schedule a hearing where both sides present evidence and the judge decides.
Receive the modified order
The new support amount takes effect from the date the petition was filed — not retroactively. This is why filing promptly matters.
Using the Division of Child Support Services (DCSS)
If your child support is enforced through the Arizona Division of Child Support Services (DCSS), you can request a review of your order through them. DCSS will review the order every three years (or sooner if there's a substantial change) and petition for modification if the Guidelines calculation differs significantly from the current order. This service is free, but the process can be slower than filing on your own or through a private attorney.
What Happens If You Don't Pay?
Falling behind on child support in Arizona has serious consequences. The court can order wage garnishment, intercept tax refunds and lottery winnings, suspend your driver's license, suspend professional licenses, place liens on your property, report the delinquency to credit bureaus, and in extreme cases, hold you in contempt of court (which can include jail time). If you're struggling to pay, file for modification immediately — don't just stop paying and hope the problem goes away.
When Child Support Ends in Arizona
Under A.R.S. § 25-320, child support generally continues until the child turns 18, or turns 19 if still enrolled in high school full-time and living with a parent. Support can also end if the child marries, is legally emancipated, enters active duty military service, or dies. For children with disabilities that prevent self-support, the court may order support to continue beyond age 18 indefinitely.
When you have multiple children and the oldest "ages out," the support order should be modified to reflect the reduced number of children. This doesn't happen automatically — you need to request it.
Need to Modify Your Child Support Order?
An experienced family law attorney can help you navigate the process efficiently.
Find a Family Law AttorneyFrequently Asked Questions
Can I modify child support without a lawyer?
Yes — the Maricopa County Self-Service Center provides forms and instructions for filing on your own. However, if the other parent contests the modification, or if there are complicated income issues (self-employment, stock options, multiple income sources), an attorney can help ensure the calculation is done correctly. Errors in the Guidelines calculation can cost you thousands over the life of the order.
Does my new spouse's income affect child support?
Generally no. A new spouse's income is not directly included in the Arizona Child Support Guidelines calculation. However, a new spouse's income may indirectly affect the analysis if it significantly reduces the parent's living expenses, freeing up more of their income for support.
How far back can a modification go?
Modifications in Arizona are effective from the date the petition is filed with the court — not retroactively to when the change occurred. If you lost your job six months ago but just filed today, you'll owe the full original amount for those six months. This is the single most important reason to file promptly when circumstances change.
Can I agree with my ex to change child support without going to court?
You can negotiate a new amount, but the agreement should be submitted to the court for approval and incorporated into a modified order. An informal agreement between parents is not enforceable — and if the other parent later changes their mind, you'll be held to the original court order, not your handshake deal.