10 percent simple, by statute
Arizona Child Support Arrears Calculator 2026
Arizona charges one of the steepest interest rates in the country on missed child support: 10 percent a year, simple, running whether or not anyone reduces the debt to a judgment. The same statute also contains a switch that turns interest off entirely for one specific kind of support debt, and telling the two apart changes real money.
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Estimate an Arizona arrears balance with interest
Estimated arrears with interest: $5,500.00
Interest of $500.00 at 10% simple per year (A.R.S. § 25-510(E)-(F)).
Assumptions
- Accrual period expressed as 12 month(s); partial months prorate.
Estimate only. The court or state agency calculation controls.
Arizona arrears interest under A.R.S. § 25-510(E)-(F); rules last reviewed 2026-08-07.
How arrears interest works in Arizona
When an Arizona support payment is missed, it becomes an arrearage, and A.R.S. section 25-510(E) starts the meter: 10 percent per year, computed as simple interest on the unpaid principal only. No judgment is needed; the statute says arrearages accrue interest whether or not they have been reduced to a final written money judgment.
The start date is slightly forgiving. Interest begins at the end of the month FOLLOWING the month in which the payment came due, so a payment missed in March starts accruing at the end of April. After that grace window, 10 percent of a $10,000 balance is $1,000 a year.
Now the switch. Subsection (F) treats "past support" differently from arrearages. Past support is a retroactive award, support for a period before any order existed, entered under section 25-320(C) or 25-809(B). If that award was reduced to judgment before September 26, 2008, it accrues the same 10 percent. On or after that date, a past-support judgment accrues NO interest for any period. Missed payments under an existing order always accrue; pre-order retroactive awards entered in the modern era never do.
The Division of Child Support Services applies these rules in its own policy: courts may suspend future interest while an obligor is incarcerated or under a qualifying disability, fee debts carry no interest, and an out-of-state order keeps its home state’s interest law unless it is registered here and modified. Arizona’s general judgment statute sets other judgments at the lesser of 10 percent or prime plus 1, but section 25-510(E) is the specific support rule and controls.
For official balances, DES runs eCalc, an arrears and payment-history tool wired to the State Case Registry. That ledger, or the court’s, is the number enforcement actually uses.
- Rate on arrearages
- 10% per year, simple, judgment or not (A.R.S. § 25-510(E))source
- Accrual starts
- End of the month after the month the payment was duesource
- Past-support exception
- Retroactive past-support judgments on or after 2008-09-26 accrue no interestsource
- Agency policy
- DCSS-POL-05-8: incarceration/disability suspensions; no interest on feessource
- Official ledger tool
- DES eCalc, tied to the State Case Registrysource
How to use this estimate
Enter the arrears principal, the sum of the missed payments, and the number of months since accrual began. The tool applies 10 percent simple annual interest across that period and shows principal, interest, and total on separate lines.
Mind the classification before trusting any interest figure. If your debt is a retroactive past-support award reduced to judgment in September 2008 or later, the interest line does not apply to you at all; only the principal is owed. If it is missed payments under an order, the full 10 percent applies.
A real DCSS ledger accrues month by month as each payment is missed, credits partial payments in a set order, and honors any court suspension of interest. One principal with one period approximates that; for the enforceable figure, pull the eCalc or court balance.
What this estimate includes
- The arrears principal you enter
- 10 percent simple annual interest for the months you specify, per § 25-510(E)
- A principal-plus-interest total with the past-support caveat attached to the rate note
What it leaves out
- Payment-by-payment accrual with the one-month statutory lag applied to each missed installment
- Partial payments, tax offsets, and DCSS crediting order
- Court-ordered interest suspensions for incarceration or disability
- Retroactive past-support judgments, which accrue nothing in the modern era
Arizona arrears FAQs
What interest rate applies to unpaid child support in Arizona?
10 percent per year, simple, under A.R.S. section 25-510(E). It attaches to support arrearages automatically, without anyone converting the debt to a money judgment, and starts at the end of the month after the month the payment was due. Compare that to Arizona’s ordinary judgment rate, which floats at the lesser of 10 percent or prime plus 1: support gets the fixed, higher treatment.
What is the past-support exception?
Section 25-510(F) splits support debt into two species. Arrearages are payments missed under an existing order; they always accrue 10 percent. Past support is a retroactive award covering time before any order existed. If a past-support judgment was entered before September 26, 2008 it accrues 10 percent from entry, but on or after that date it accrues no interest for any time period. People routinely assume all back support earns interest in Arizona; for modern retroactive awards, none of it does.
Is Arizona child support interest simple or compound?
Simple, on principal only. Interest that has already accrued does not itself earn interest. At 10 percent that still doubles the principal in ten years if nothing is paid, which is why decades-old Arizona cases can carry interest rivaling the missed payments themselves.
Can interest be paused or waived?
Paused, sometimes: DCSS policy recognizes court authority to suspend future interest while the obligor is incarcerated or has a qualifying disability. The principal keeps its character either way, and vested installments cannot be retroactively forgiven; modification only reaches forward from service of a petition. Arizona has no obligee-waiver mechanism written into the interest statute.
How do arrears payments interact with the current support order?
Section XVI of the child support guidelines requires courts setting an arrears payment to consider the interest that keeps accruing under section 25-510. If the monthly arrears payment is set below the monthly interest accrual, the balance grows even while the obligor pays faithfully, and the court must make findings before ordering that. It is the classic treadmill problem, and Arizona makes judges face it explicitly.
Where do I get the official arrears balance?
For DCSS-enforced cases, DES eCalc computes balances from the State Case Registry’s charge and payment history; otherwise the clerk’s ledger controls. This page approximates scale so you can sanity-check a demand letter or plan a payoff, but employers, courts, and tax intercepts act on the official number.
Official sources
Official sources last verified: .
- A.R.S. § 25-510 (support arrearages accrue 10% simple interest from the end of the month after the payment is due; past-support judgments on/after 2008-09-26 accrue NO interest)
Arizona State Legislature (azleg.gov) Last checked
- DCSS-POL-05-8 v.2, Interest on Past Support and Support Arrears (corroborates 25-510(E)-(F); interest suspension during incarceration/disability; no interest on fee debts)
Arizona DES Division of Child Support Services (dcsspolicy.azdes.gov) Last checked
- A.R.S. § 44-1201 (interest; judgments at the lesser of 10% or prime plus 1%; 25-510(E) is the specific support-arrears rule and controls for support)
Arizona State Legislature (azleg.gov) Last checked
- DES eCalc: official arrears and payment-history tool tied to the State Case Registry
Arizona DES (extranet.azdes.gov) Last checked
Reviewed by SupportDecode Editorial Team Page content reviewed Sources Methodology Update log
Changelog: page first published with the 10 percent simple-interest rule, the accrual start date, and the past-support exception. Material changes are dated in the update log.