How to Use the Idaho Child Support Calculator
Enter what you know and press Calculate Estimate. The calculator follows the Idaho Child Support Guidelines in Idaho Rules of Family Law Procedure (IRFLP) Rule 120, as amended effective July 1, 2025.
- Enter each parent's gross monthly income before taxes. The calculator converts it to annual Guidelines Income.
- Choose the number of children and the parent the children live with most of the time.
- Enter the overnights a year with the other parent. More than 25% (92 or more) uses the shared custody formula.
- Add the children's health insurance premium and any work-related child care, and say which parent pays them.
Your numbers are sent with the form, not placed in the page address, and this site does not store them. This is a planning estimate. An Idaho court decides the actual amount.
Idaho Child Support Rules in 2026
Looking for new child support guidelines in Idaho for 2026? Rule 120 was adopted July 1, 2021, amended effective July 1, 2022, and most recently amended effective July 1, 2025. The 2025 change allows courts to count student loan proceeds as potential income only if they are actually paid to the parent-student and used for expenses other than education (Rule 120(e)(3)). The schedules themselves did not change, and we found no amendment to Rule 120 effective in 2026.
A change in the rules does not automatically change an existing order. A parent generally has to ask the court to modify it.
How Idaho Calculates Child Support
Idaho uses an income shares model based on gross income before taxes (Guidelines Income), adjusted for support and maintenance paid in other cases, maintenance in the current case and other children in the home.
- Add both parents' annual Guidelines Income.
- Apply the percentage schedule for the number of children to the combined income, bracket by bracket.
- Split the result by each parent's share of combined income. The parent the children do not live with pays their share.
The Idaho Child Support Schedules
Each percentage applies only to the part of combined annual Guidelines Income in that bracket:
| Combined annual income bracket | 1 child | 2 children | 3 children | 4 children | 5 children |
|---|
| First $10,000 | 18% | 26% | 30% | 33% | 36% |
| Next $10,000 | 17% | 25% | 29% | 32% | 35% |
| Next $10,000 | 15% | 23% | 27% | 30% | 33% |
| Next $10,000 | 14% | 22% | 26% | 29% | 32% |
| Next $10,000 | 13% | 20% | 24% | 27% | 30% |
| Next $20,000 | 12% | 17% | 20% | 22% | 24% |
| Next $20,000 | 9% | 13% | 16% | 18% | 20% |
| Next $20,000 | 6% | 9% | 12% | 14% | 16% |
| Next $20,000 | 5% | 8% | 11% | 13% | 15% |
| Next $20,000 | 5% | 8% | 11% | 13% | 15% |
| Next $290,000 (to $440,000) | 5% | 8% | 11% | 13% | 15% |
For example, with one child and $60,000 of combined income: 18% of $10,000 + 17% of $10,000 + 15% of $10,000 + 14% of $10,000 + 13% of $10,000 + 12% of $10,000 = $8,900 a year. Above $440,000 the court applies the schedule to the first $440,000 and considers other factors. The schedules are not a limit for more than five children.
Shared Custody in Idaho
If the children spend more than 25% of the overnights with each parent (92 or more a year), Rule 120 uses a shared custody formula:
- Multiply the basic obligation by 1.5.
- Multiply by each parent's income share.
- Multiply each result by the percentage of time the children spend with the other parent.
- Offset the two amounts. No parent pays more than they would without the adjustment.
With 25% or fewer overnights, the regular calculation is used, though extended visits of 14 days or more may justify a reduction for that time.
Idaho Child Support Examples
In each example the children live with Parent B. Amounts are monthly and come from this calculator.
Example 1: One child
A earns $5,000 and B earns $3,000 a month ($96,000 a year combined). The schedule gives $12,260 a year ($1,021.67 a month), and A's 62.5% share is $638.54 a month.
Example 2: Two children with insurance
A earns $6,000 and B earns $4,000, and B pays a $300 premium. A's 60% share of $1,683.33 is $1,010, plus 60% of the premium ($180): $1,190 a month.
Example 3: Shared custody
A earns $7,000 and B earns $3,000, one child, 146 overnights with A. A pays $510 a month.
Example 4: High income
A earns $30,000 and B earns $10,000 a month with three children. The schedule applies to the first $440,000 a year: A pays $3,718.75 a month.
These are illustrations produced from the rule, not court rulings.
Frequently Asked Questions About Idaho Child Support
Is this the official Idaho child support calculator?
No. ChildSupportCalculator.xyz is an independent tool and is not affiliated with the State of Idaho or its courts. It applies IRFLP Rule 120. A court sets the actual amount.
How is child support calculated in Idaho?
Both parents' gross annual incomes are added, a percentage schedule for the number of children is applied bracket by bracket, and the result is split by income share.
Does Idaho use gross or net income?
Gross income before taxes (Guidelines Income), with adjustments for other support, maintenance and other children in the home.
How does shared custody work in Idaho?
If each parent has more than 25% of the overnights, the basic obligation is multiplied by 1.5 and by each parent's income share and the other parent's time share, and the two amounts are offset.
What is the minimum child support in Idaho?
There is a rebuttable presumption of at least $50 per child per month.
Is there an income cap for child support in Idaho?
The schedules apply to the first $440,000 of combined annual income. Above that, the court considers additional factors.
Is child care included in Idaho child support?
Not in the basic amount. The court may order reasonable work-related child care shared by income, usually paid directly between the parents.
How is health insurance handled in Idaho?
The children's premium and uncovered medical costs are shared by income. The premium share may be added to or credited against child support.
Did Idaho change its child support rules recently?
Rule 120 was last amended effective July 1, 2025, mainly about counting student loan proceeds as potential income. The schedules did not change.
Does the Idaho calculator need my personal details or a login?
No. This site needs no login and does not store your numbers.
Official Idaho Child Support Resources
Published: October 17, 2026
Last reviewed: October 17, 2026
Researched and reviewed by Eric John, founder and editor, using official state statutes and guidance. How we build and check our calculators · Corrections
