How Idaho calculates child support
- Each parent’s gross income is reduced by other child support and maintenance orders, maintenance in this case and the guideline amount for their other children living in their home.
- The schedule takes a falling percentage of each slice of the parents’ combined annual income (for example 26%, 25%, 23% … for two children), up to $440,000. Each parent owes their income share of that amount.
- When one parent has the children 25% of overnights or less, that parent pays their share. When each parent has more than 25%, the amount is multiplied by 1.5, each share is multiplied by the other parent’s share of overnights, and the two are offset, never more than the standard amount.
- Work-related child care and the children’s health insurance premiums are shared in proportion to income.
- The guidelines presume at least $50 per child per month, and ask the court to review closely when the paying parent’s income is under $800 a month.
What the calculator asks
- How many children is the support for?
- How will overnights with the children be shared?
- How many overnights a year are the children with you?
- Your gross income for the year
- Child support or maintenance you pay each year for another relationship
- Spousal maintenance ordered in this case that you pay each year
- How many of your own children from another relationship live with you?
- The other parent’s gross income for the year
- Child support or maintenance the other parent pays each year for another relationship
- Spousal maintenance ordered in this case that the other parent pays each year
- How many of the other parent’s own children from another relationship live with them?
- Work-related child care you pay each month
- Work-related child care the other parent pays each month
- Health insurance premiums you pay for the children each month
- Health insurance premiums the other parent pays for the children each month
It never asks for names, Social Security numbers or account numbers, and your answers are not saved.
What the estimate leaves out
- The tax-benefit adjustment for claiming the children (worksheet line 6c, I.R.F.L.P. 120(g)(3) tax tables)
- Split and mixed custody, and more than five children
- Uninsured medical costs, transportation costs and extended-visit reductions
- Disability or retirement dependency benefits paid for the children (I.R.F.L.P. 120(g)(5))
- Support above the schedule for combined income over $440,000 a year, and deviations from the guidelines
When a situation is outside what the calculator covers, it says so and points you to the official worksheet instead of guessing.
Official sources
- Idaho Rules of Family Law Procedure 120, Idaho Child Support Guidelines (as amended eff. July 1, 2025)
- I.R.F.L.P. 120 as amended effective July 1, 2022 (PDF; same schedule)
- Standard Child Support Worksheet, I.R.F.L.P. Form 6
- Shared, Split or Mixed Custody Child Support Worksheet, I.R.F.L.P. Form 7
Ready to estimate? The calculator shows each worksheet line so you can check it against the official form.
Open the Idaho calculator →An estimate from the published guideline formula, not a prediction of a court order. The official court worksheet and the court’s decision control. General information, not legal advice. LawCat is not a law firm.