Idaho Child Support Calculator

This free calculator estimates your monthly child support obligation under Idaho’s Income Shares Model, using the same marginal-rate brackets and shared-custody offset formula found in IRFLP Rule 120. Enter each parent’s gross monthly income, the number of children, and the custody arrangement to see an estimate update instantly.

How This Calculator Works

Idaho determines child support by applying marginal rate brackets to the parents’ combined annual gross income (Rule 120(i)(1)), producing a base obligation that scales with the number of children. That base amount is then split between the parents proportional to their share of combined income.

• Primary custody (Rule 120(i)(3)(B)): the non-custodial parent pays their income share of the base obligation, subject to a $50-per-child minimum (Rule 120(c)(4)).
• Shared custody (Rule 120(i)(4), >25% overnights each parent): the base obligation is multiplied by 1.5, apportioned by both income share and the other parent’s percentage of overnights, then offset between the two parents.

This tool provides an estimate only — it is not legal advice, and courts retain discretion to deviate from the guideline calculation based on exceptional circumstances under Rule 120(b)(3). For a precise number or help applying it to your case, request a consultation with one of our Idaho child support attorneys.

Looking for the full overview of how Idaho child support works, healthcare provisions, and enforcement? Visit our Idaho Child Support page.

Frequently Asked Questions

Is this calculator’s result legally binding?

No. This tool provides an estimate based on Idaho’s guideline formula. Only a court order, or a stipulation approved by the court, establishes an actual child support obligation.

What counts as income under Idaho’s guidelines?

Per Rule 120(e), ICSG income is gross income minus certain deductions. Voluntary overtime and second-job income are generally excluded from the calculation.

Is there a minimum child support amount?

Yes. Rule 120(c)(4) sets a minimum of $50 per month per child, which applies even at very low combined incomes.

Can the court order a different amount than this estimate?

Yes. Courts may deviate from the guideline calculation under Rule 120(b)(3) based on exceptional circumstances.

Disclaimer: This calculator provides a general estimate based on Idaho’s statutory child support guidelines and should not be considered legal advice. Consult an attorney for guidance specific to your situation.