Interest on Child Support Arrears in Idaho: Rate, Simple vs. Compound and When It Applies
The Idaho child support interest rate that applies to judgments is 5% plus a base rate set each July 1, 8.875% for the current fiscal year. It applies to money due on a judgment; we found no automatic interest on unpaid support installments.
What is the interest rate on judgments in Idaho?
The legal rate of interest on money due on the judgment of any competent court or tribunal is 5% plus the base rate in effect when the judgment is entered. The State Treasurer sets the base rate each July 1 as the weekly average one-year Treasury yield rounded up to the nearest one-eighth percent, and the rate announced on July 1 applies to judgments declared during the next 12 months (Idaho Code 28-22-104(2)). The Treasurer lists 8.875% for the current fiscal year, July 1 to June 30, and 9.125% for the year before (Idaho State Treasurer).
Does that rate apply to unpaid child support?
It applies to money due on a judgment. We found no Idaho provision that adds interest automatically to each unpaid support installment, and the statutes we read make a support decree modifiable only as to later installments (32-709). So whether and from when interest runs on your arrears depends on whether they were reduced to a judgment and on the court’s order. Ask Child Support Services or the clerk for the judgment and its interest terms.
How much could Idaho interest add? A scenario table
If interest ran at 8.875% simple on each unpaid $500 monthly installment, the newest just due, the figures would be:
| Case | Interest at 8.875% | Total owed |
|---|---|---|
| 12 unpaid installments of $500 | $244.06 | $6,244.06 |
| 24 unpaid installments of $500 | $1,020.63 | $13,020.63 |
| 36 unpaid installments of $500 | $2,329.69 | $20,329.69 |
This is a scenario, not a statement that Idaho charges it on every installment. Test any rate in the Idaho arrears calculator.
Is the Idaho judgment rate fixed for the life of the judgment?
The statute says the legal rate announced on July 1 operates as the rate applying for the succeeding twelve months to all judgments declared during that period, and that interest and principal are calculated on a 365-day year. The statute does not say in so many words whether the rate changes later, so read the judgment and ask the court.
How are Idaho child support payments applied?
Child Support Services collects withheld income and sends it to the obligee; the withheld amount cannot exceed 50% of disposable earnings, or current support plus the arrearage payment ordered if less (32-1210(3)). Ask for a payment history to see how payments were applied.
What does the Idaho statute say about interest on a judgment?
The statute applies to money due on the judgment of any competent court or tribunal, and says interest and principal are calculated on a 365-day year. It does not mention child support, so the specific facts of your judgment decide the answer (28-22-104(2)).
Where do you get the official figure?
From Child Support Services if it has your case, or the court clerk’s records. See whether arrears expire or can be forgiven and file to modify if your circumstances changed.
Frequently asked questions
What is the Idaho judgment interest rate?
5% plus a base rate set each July 1; 8.875% for the current fiscal year.
Does Idaho charge interest on unpaid child support installments?
We found no provision adding interest automatically to installments; the judgment rate applies to money due on a judgment.
Who sets the Idaho judgment interest rate?
The Idaho State Treasurer, each July 1.
Is Idaho judgment interest simple or compound?
The statute calculates interest and principal on a 365-day year and does not provide for interest on interest; this calculator uses simple interest.
Where can I check my Idaho child support balance?
With Child Support Services or the court clerk.
Official sources
- Idaho Code 32-1205: income withholding upon a delinquency
- Idaho Code 32-1210: employer duties; 50% cap
- Idaho Code 7-1402: license suspension definitions
- Idaho Code 7-1206: department lien and credit reporting
- Idaho Code 7-1203: available remedies
- Idaho Code 28-22-104: legal rate of interest
- Idaho State Treasurer: legal rate of interest by fiscal year
- 42 U.S.C. 652(k): denial of passports
A local family law attorney can review your situation — many offer a free consultation.
This is general information, not legal advice. It is based on the cited Idaho statutes, rules and court opinions, and every case turns on its own facts. Confirm how the law applies to your situation with a licensed Idaho attorney.