Reviewed for current 2026 law
Missouri Child Support Arrears Calculator
Model the support-specific one-percent monthly simple-interest rule.
Reviewed by SupportDecode Editorial Team Page content reviewed Sources Methodology Update log
arrears calculator
Estimated arrears with interest: $5,006.00
Interest of $6.00 at 0.12% simple per year (Mo. Rev. Stat. § 454.520).
| Line item | Amount |
|---|---|
| Arrears principalMo. Rev. Stat. § 454.520 — interest on delinquent support and maintenance (Missouri Revisor of Statutes) | $5,000.00 |
| Simple interest at 0.12% per year for 12 month(s) (Mo. Rev. Stat. § 454.520)One percent simple interest accrues at the close of the last business day of each month on the qualifying arrearage, excluding that month’s installments.Mo. Rev. Stat. § 454.520 — interest on delinquent support and maintenance (Missouri Revisor of Statutes) | $6.00 |
| Arrears principal plus interestMo. Rev. Stat. § 454.520 — interest on delinquent support and maintenance (Missouri Revisor of Statutes) | $5,006.00 |
Assumptions
- Accrual period expressed as 12 month(s); partial months prorate.
Estimate only. The court or state agency calculation controls.
Missouri arrears interest under Mo. Rev. Stat. § 454.520; rules last reviewed 2026-08-09.
Missouri uses monthly simple interest
Section 454.520 applies one percent per month to modern Missouri support judgments.
Interest accrues at month end on the qualifying arrearage after excluding that month’s installments, so a yearly estimate cannot replace a dated ledger.
Use a month-by-month ledger for payoff
Verify order date, each installment, every payment, and allocation before relying on a balance.
What this estimate includes
- Equivalent 12% annual simple estimate
What it leaves out
- Monthly ledger reconstruction
- Historical rate transitions
- Official payoff
Missouri arrears calculator FAQs
Does interest compound?
No. Section 454.520 expressly says simple interest.
When does it accrue?
At the close of the last business day of each month.
Is the current month’s installment included?
The statute excludes that month’s installments from the month-end interest base.
Did older orders have different rates?
Yes; the statute preserves historical transitions for pre-September 1982 orders.
Are payments interest first?
No payment is treated as interest until the support arrearage is satisfied.
Is an affidavit needed?
Execution for interest generally requires the statutory payment-history affidavit and computation statement.
Official sources
Official sources last verified: .
- Mo. Rev. Stat. § 454.520 — interest on delinquent support and maintenance
Missouri Revisor of Statutes Last checked
Changelog: page reviewed . Material changes appear in the update log.