Idaho Child Support Calculator
Estimate Idaho child support under the current guidelines, I.R.F.L.P. 120 as amended effective July 1, 2025. The quick estimate below gives base support; the full calculator adds health insurance, child care, the tax benefit, step-down dates and the official worksheet.
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How Idaho child support is calculated
- Guidelines Income for each parent. Gross income from all sources, including potential (imputed) income, less support paid under other orders, spousal maintenance and a deduction for other children in the home. I.R.F.L.P. 120(e)–(f)
- Basic obligation. Add both incomes and apply the schedule’s percentages, slice by slice, for the number of children. I.R.F.L.P. 120(i)(1)
- Each parent’s share is in proportion to their income. I.R.F.L.P. 120(c)(1)
- Custody adjustment. With 25% or fewer overnights, a parent pays their share. If each parent has more than 25%, the shared-custody formula applies. I.R.F.L.P. 120(i)(3)–(6)
- Adjustments for child care, health insurance and the tax benefit. I.R.F.L.P. 120(g)
Read the full walkthrough, with the complete schedule →
The rule’s own example
Rule 120 works through a case with two children where one parent earns $25,000 a year and the other $10,000. Their combined $35,000 is applied to the two-child schedule:
- 26% of $10,000 = $217/month
- 25% of $10,000 = $208/month
- 23% of $10,000 = $192/month
- 22% of $5,000 = $92/month
That is a basic obligation of $709 a month. The parent with 25% or fewer overnights earns 71% of the combined income and pays $506 a month. I.R.F.L.P. 120(i)(3)(B)
Common situations
- Shared and 50/50 custody: how the 25% line and the 1.5 multiplier work
- Health insurance, child care and the tax benefit
- The child support worksheet (Forms 5, 6 and 7)
Frequently asked questions
How is child support calculated in Idaho?
Idaho uses an income shares model (I.R.F.L.P. 120). Both parents' Guidelines Income is added together, a schedule of percentages gives the basic support obligation for that combined income and number of children, and each parent is responsible for their share in proportion to their income. The parent with 25% or fewer of the overnights pays their share to the other parent; if each parent has more than 25%, the shared-custody formula applies.
How many overnights count as shared custody in Idaho?
More than 25% of the overnights in a year with each parent (I.R.F.L.P. 120(i)(4)). Counting overnights out of 365, that means 92 or more. At 91 or fewer, the standard (primary custody) calculation applies.
What is the minimum child support in Idaho?
There is a rebuttable presumption that support is at least $50 per month per child, and when the paying parent earns less than $800 a month the court should carefully review incomes and living expenses (I.R.F.L.P. 120(c)(4)).
Is there an income cap?
The schedule covers combined Guidelines Income up to $440,000 a year. Above that, support on the first $440,000 is calculated normally and the court may order more after considering the factors in I.R.F.L.P. 120(i)(7).
When does child support end in Idaho?
Support is calculated for children under 18, or up to 19 while the child is pursuing a high school education (I.R.F.L.P. 120(a)). The judgment must state the support due for the remaining children as each child is no longer entitled to it, recalculated from the schedule rather than reduced proportionally (I.R.F.L.P. 120(j)).
Is this the official Idaho calculator?
No. This is an independent calculator, not affiliated with the State of Idaho, the Idaho courts or the Idaho Department of Health and Welfare. It implements the court rule (I.R.F.L.P. 120) and fills the court’s own worksheet forms, but the court decides the final amount. Verify results before filing.