Idaho Child Support Laws (2026): Guidelines & Calculator

Idaho calculates child support using the Income Shares Model under IRFLP Rule 120. Courts add both parents' gross monthly incomes, apply graduated percentages based on the number of children, and assign each parent a share of the total obligation proportional to their income. Use the Idaho child support calculator below to estimate a guideline amount, or open the Idaho child support calculator for a full-page version.

How Idaho Calculates Child Support

Idaho follows the Income Shares Model under Idaho Rules of Family Law Procedure (IRFLP) Rule 120. This model starts with the combined gross monthly income of both parents, then applies graduated percentages based on the number of children.

Each parent pays a share of the total support obligation in proportion to their percentage of the combined income. For example, if one parent earns $6,000 per month and the other earns $4,000, the first parent is responsible for 60% of the calculated obligation and the second parent covers 40%.

The Idaho Supreme Court publishes the Basic Monthly Child Support Guidelines Schedule, which lists specific support amounts for combined income levels ranging from $800 per month up to the guideline cap. The schedule was last comprehensively updated effective July 1, 2022. A further amendment effective July 1, 2025 revised Rule 120(e)(3), which governs how courts impute potential income to voluntarily unemployed or underemployed parents.

Income Percentage Brackets

Idaho applies graduated percentages to brackets of combined parental income. The percentages decrease as income rises, reflecting the principle that higher-income families spend a smaller proportion of income on child-rearing.

For one child, the guidelines start at 18% of the first income bracket and gradually step down to 5% for the highest bracket. For two children, the starting percentage is 26%, stepping down to 8%. For three children, rates begin at 30% and decrease to 11%.

The guideline amounts are cumulative across brackets. Courts add the calculated amount from each bracket together to reach the total basic monthly child support obligation.

Income Cap

The guidelines apply to combined parental income up to $440,000 per year ($36,667 per month). For families earning above that threshold, the court considers additional factors when setting support, including the child's standard of living before the parents separated, the child's educational and emotional needs, and any special circumstances.

Minimum Support Amount

Idaho law creates a rebuttable presumption that each parent should pay at least $50 per month per child. When the paying parent earns less than $800 per month, courts review both parents' income and expenses carefully. The goal is to set a support amount that does not deny the paying parent the means for self-support at a minimum subsistence level.

What Counts as Guidelines Income

Under IRFLP Rule 120, "Guidelines Income" means gross income from virtually all sources before taxes. The guidelines cast a wide net to capture total earning capacity.

Sources of Income

Idaho courts count the following as income for child support calculations:

• Salaries, wages, commissions, and bonuses
• Self-employment income (minus ordinary and necessary business expenses)
• Dividends, interest, and investment income
• Rental income and royalties
• Pensions, annuities, and Social Security benefits
• Workers' compensation and disability benefits
• Unemployment insurance benefits
• Alimony or maintenance received from a prior relationship
• Education grants, scholarships, and financial aid (to the extent they reduce living costs)
• Veterans' benefits
• Trust income and capital gains

Fringe Benefits

Employment benefits that reduce a parent's personal living expenses also count as income. Examples include a company car, employer-provided housing, gas cards, and reimbursed meals. Courts evaluate the fair market value of these benefits when calculating Guidelines Income.

Overtime and Second Job Income

Overtime pay and second-job earnings may be excluded from the calculation if three conditions are met:

1. The overtime is voluntary (not required as a condition of employment).
2. The parent works full-time for at least 48 weeks per year at a primary job.
3. The parent has not changed jobs to manipulate the support calculation.

If the overtime is mandatory or the parent historically relied on overtime income, courts will likely include it.

Imputed (Potential) Income

When a parent is voluntarily unemployed or underemployed, Idaho courts calculate support based on that parent's potential earning capacity. This prevents a parent from reducing income on purpose to lower child support.

However, courts will not impute income to a parent who is:

• Physically or mentally incapacitated
• Incarcerated (incarceration cannot be treated as voluntary unemployment)
• Caring for a child under 6 months old
• Employed full-time in the same or similar occupation held for at least 6 months before the parents' separation

Adjustments That Reduce Gross Income

The following deductions are subtracted from gross income before calculating each parent's Guidelines Income:

• Court-ordered child support paid for children from other relationships
• Court-ordered spousal maintenance payments
• Voluntary support payments for children from another relationship (if a consistent pattern of payment exists)
• A guideline support deduction for other natural or adopted children living in the parent's home

Shared Custody and Parenting Time Adjustments

Idaho's guidelines recognize that parenting time affects how much each parent spends on the child directly. The rules provide different calculations depending on custody arrangements.

Standard Custody (One Parent Has Primary Custody)

When one parent has the child for more than 75% of overnights per year, the standard calculation applies. The noncustodial parent pays their proportional share of the basic guideline amount to the custodial parent.

Shared Physical Custody (More Than 25% Overnights Each)

When the child spends more than 25% of annual overnights with each parent, Idaho applies a shared custody formula:

1. Multiply the basic child support guideline amount by 1.5.
2. Multiply the result by each parent's percentage of combined income.
3. Multiply each parent's share by the percentage of time the child spends with the other parent.
4. Offset the two amounts. The parent who owes more pays the difference to the other parent.

A parent under the shared custody formula will never pay more than they would have paid under a sole custody arrangement.

Extended Visitation Credit

For the noncustodial parent who has 25% or fewer overnights, the guidelines allow a reduction when the child stays for 14 or more consecutive days. A reasonable reduction is 50% of the daily support rate during those extended visits.

Split Custody

When each parent has primary custody of at least one child from the same relationship, Idaho applies a split custody formula. The basic obligation is multiplied by 1.5, pro-rated among all the children, and offset between the parents.

Additional Expenses Beyond Basic Support

The basic guideline amount covers ordinary child-rearing costs. Idaho requires parents to share certain additional expenses proportionally.

Child Care Costs

Work-related child care expenses are divided between parents based on each parent's share of combined Guidelines Income. Parents pay these costs directly to each other unless they agree to a different arrangement.

Health Insurance and Medical Expenses

The parent who can obtain appropriate health insurance coverage at a lower cost should carry the policy. Both parents share the premium cost and out-of-pocket medical expenses in proportion to their income.

Any claimed health care expense exceeding $500 for a single course of treatment requires advance approval from both parents or a court order.

Transportation for Parenting Time

Courts may allocate transportation costs for parenting time visits. Factors include the financial resources of both parents, the cost of exercising parenting time, and the reasons behind any parental relocation.

Tax Dependency Benefits

The dependency exemption and related tax benefits go to the parent who receives the greater tax benefit. The other parent is entitled to a proportional share of the benefit based on their percentage of Guidelines Income.

How to Modify a Child Support Order in Idaho

Under Idaho Code Section 32-709, child support orders can only be modified upon a showing of a substantial and material change of circumstances. The modification applies only to payments due after the motion is filed, not to past-due amounts.

Common Grounds for Modification

• A significant increase or decrease in either parent's income
• A change in parenting time or custody arrangements
• A change in the child's needs (medical, educational, or otherwise)
• Changes in health insurance costs or availability
• Relocation of a parent that affects transportation costs
• A recalculation under the guidelines that produces a materially different amount

Arrears Credit for Changed Custody

Idaho Code Section 32-709(2) allows courts to grant a credit against child support arrears when the child has lived primarily with the paying parent for more than 120 consecutive days with the custodial parent's knowledge and consent.

How to Request a Modification

You have two options:

Through Idaho Child Support Services (CSS): Contact Idaho Child Support Services to request a review and modification. CSS charges a fee of $310 for a default modification, $500 for a stipulated modification, or $575 if the case goes to trial. These fees became effective October 2025.

Through the court directly: You may hire a private attorney or represent yourself and file a modification petition with the court. Court self-help forms are available from the Idaho Courts Self-Help Center.

Does Remarriage Affect Child Support?

Remarriage alone does not change child support in Idaho. A new spouse's income is generally not counted when calculating support. Children born after the existing support order are not automatically considered in modification proceedings.

However, if remarriage substantially changes a parent's overall financial situation, it could serve as evidence of a material change of circumstances in a modification case.

Enforcement of Child Support Orders

The Idaho Department of Health and Welfare's Child Support Services (CSS) division enforces child support orders using multiple tools authorized by state and federal law.

Income Withholding

Income withholding is the primary enforcement method. Under Idaho Code Section 32-1204, the court shall order income withholding in all support orders, effective the date of the order, unless it grants one of the narrow exceptions in subsection (2): a specific written finding of good cause, or a written alternative agreement between the parties and the department that the court approves. Withholding takes effect once an employer is identified, and the employer deducts the support amount directly from the parent's wages or salary before the parent receives their paycheck.

Other Enforcement Tools

The $2,000 license-suspension figure is a ceiling, not a floor. Idaho Code Section 7-1402(3) defines a delinquency as unpaid support equal to or greater than the total support owing for at least 90 days or $2,000, whichever is less, and Section 7-1403 makes a parent with that delinquency subject to license suspension. For most orders below roughly $667 per month, the 90-day figure is the smaller one and controls. A parent ordered to pay $300 per month is exposed at about $900 in arrears, not $2,000.

Contempt of Court

A parent who fails to pay court-ordered child support may face contempt of court proceedings. Penalties can include fines and jail time, although courts treat incarceration as a last resort because it prevents the parent from earning income.

Under federal law, intentionally crossing state lines to avoid child support or owing more than $10,000 in arrears (or more than two years of unpaid support) can result in felony charges under the Deadbeat Parents Punishment Act (18 U.S.C. Section 228).

When Child Support Ends in Idaho

Under Idaho Code Section 32-706, child support ordinarily continues until the child reaches age 18.

Extension to Age 19

If the child is still attending high school after turning 18, the court may extend support until the child either finishes high school or reaches age 19, whichever comes first. Idaho does not authorize child support for college or post-secondary education under these guidelines.

Early Termination

Child support may end before age 18 if the child:

• Becomes legally emancipated through a court order
• Gets married
• Joins the armed forces

Statute of Limitations on Arrears

Under Idaho Code Section 5-245, a child support arrearage judgment may be collected at any time before that judgment expires or is renewed: there is no fixed deadline tied to the child's age of majority. Idaho does not charge interest on retroactive or back child support, though interest may apply to court judgments for arrears.

Applying for Child Support Services in Idaho

The Idaho Department of Health and Welfare operates Child Support Services (CSS), which helps families with:

• Establishing paternity through genetic testing ($55 per person) or voluntary acknowledgment
• Establishing a child support order ($310 to $575, depending on case complexity)
• Modifying existing orders when circumstances change
• Enforcing orders through income withholding, tax intercepts, and other tools
• Collecting and distributing payments

Application and Fees

The application fee is $25. Parents receiving SNAP, Medicaid, or cash assistance through the Idaho Department of Health and Welfare are exempt from the application fee.

Legal service fees are assessed based on the type of service needed and are generally not due upfront. CSS may deduct fees from future support collections. Attorney services are billed at $100 per hour and paralegal services at $50 per hour when applicable.

You can apply online or contact your local CSS office through the Idaho Child Support Services portal.

More Idaho Laws

• Idaho Alimony Laws
• Idaho Child Custody Laws
• Idaho Divorce Laws