Quick answer: In Missouri, delinquent child support draws simple interest of 1% a month, accruing at the end of each month on the arrearage less that month’s installment. Interest is not collected until the whole support arrearage is paid. Withholding is mandatory at one month behind, and a license can be suspended after 60 days’ notice at three months or $2,500.
This Missouri child support arrears calculator adds up the unpaid installments and the 1% monthly interest under RSMo 454.520, and flags the withholding, license and passport thresholds. A change to the order cannot reach back before service, so serve early.
Missouri child support arrears and interest at a glance
| Rule | What Missouri says |
|---|---|
| Interest | Simple interest of 1% a month on delinquent support for judgments entered on or after September 1, 1982 (RSMo 454.520.3-4) |
| Method | Accrues at the close of each month on the arrearage less that month’s installments; automatic and attached to the judgment (454.520.4) |
| Payments | No payment counts as interest until the whole support arrearage is satisfied (454.520.4) |
| Withholding | Mandatory, without exception, once the obligor is one month’s support behind (454.505.1) |
| Licenses | Arrears of three months of support or $2,500, whichever is less, at service of a 60-day notice (454.1003) |
| Liens | Workers’ compensation (over $100) and vehicles, boats and trailers (over $1,000 of support and over $3,000 of value) (454.517; 454.516) |
How do child support arrears work in Missouri?
- Interest and method. See the Missouri child support interest rate.
- Collection. See what happens if you do not pay child support in Missouri.
- Time limits and forgiveness. See whether Missouri child support arrears expire or can be forgiven.
What does this arrears calculator check?
You enter the monthly support, the number of installments unpaid and the monthly rate (1% by default). The calculator adds simple interest the statutory way, month by month on the balance less the month’s own installment, and flags the one-month withholding trigger, the license trigger and the $2,500 passport line. It does not model partial payments. To change the amount going forward, see the Missouri child support modification calculator, and for when the obligation stops, the Missouri child support end date calculator.
Frequently asked questions
Does Missouri charge interest on child support arrears?
Yes. Delinquent support from judgments entered on or after September 1, 1982 draws simple interest of 1% a month.
How is Missouri child support interest calculated?
At the close of each month, the arrearage less that month's installments is multiplied by 1%, and the monthly amounts are added up.
Is Missouri child support interest collected right away?
Interest attaches automatically, but no payment is treated as interest until the entire support arrearage has been paid.
When can a Missouri license be suspended for unpaid child support?
When the arrearage is at least three months of support or $2,500, whichever is less, when notice is served; the notice gives 60 days to pay, set a payment plan or ask for a hearing.
When does Missouri income withholding become mandatory?
Once the obligor is delinquent by one month's total support obligation.
Official sources
- RSMo 454.520: interest on delinquent support
- RSMo 454.505: wage withholding
- RSMo 454.1003: license suspension
- RSMo 454.1005: license suspension hearing
- RSMo 454.517: workers’ compensation lien
- RSMo 454.516: lien on vehicles
- 15 U.S.C. 1673: restriction on garnishment
- 42 U.S.C. 652(k): denial of passports