Child support in Idaho.
What the state’s own guideline says, where the number comes from, and the one figure that moves it more than anything you will argue about.
See a different stateIdaho
Idaho starts from the principle that 'both parents must financially support their child' and that the responsibility 'should be divided proportionally to their Guidelines Income.' The two incomes are combined, a schedule gives the total the family should spend on the children, and each parent owes their percentage share. If the children spend more than a quarter of their overnights with each parent, a shared-custody formula takes over.
How Idaho works out the number
Authority: Idaho Rule of Family Law Procedure 120, Idaho Child Support Guidelines, as amended June 3, 2025, effective July 1, 2025Yes, and the trigger is more than 25% of overnights – that is more than roughly 91 overnights a year with each parent. Shared custody applies 'if the child spends more than 25% of the overnights in a year with each parent.' Then 'the Basic Child Support Guideline obligation will be multiplied by 1.5,' each parent's share is figured by income percentage, and each is multiplied by the share of time the child spends with the other parent, with one parent paying the difference. There is a safety valve: 'in no event will a parent be required to pay more support than the parent would have paid had there not been split or shared custody.'
Use the state’s own calculator, not ours
Idaho publishes this itself, free. It is called IRFLP Form 6, Standard Child Support Worksheet; IRFLP Form 7, Shared, Split or Mixed Custody Worksheet. We are not going to build a competing calculator and ask you to trust it — this is the one a judge will recognize.
Open the Idaho calculator →What goes into the calculation
What counts as income
Guidelines Income is 'gross income (before taxes) of the parents and if applicable, employment benefits and/or potential income; less adjustments.' Self-employment income is gross receipts minus ordinary and necessary expenses, with straight-line depreciation and a deduction for one-half of self-employment Social Security tax. Overtime and second-job income get special treatment: the court may leave them out if it finds all of these – 'either the overtime pay is not a condition of employment or the second job is voluntary'; 'the second job is part-time employment or the overtime pay is by the hour'; the person did not change jobs to manipulate support; 'the person is paid for full time for at least 48 weeks out of the year'; and 'child support payments are based upon current income.' Bonuses are part of gross income.
When a judge can treat you as earning more
'If a parent is voluntarily unemployed or underemployed, child support will be based on gross potential income, except that potential income should not be included for a parent that is physically or mentally incapacitated.' Two protections matter: a parent is not underemployed if they have been 'gainfully employed on a full-time basis at the same or similar occupation … for more than six months before the filing of the action,' and 'ordinarily, a parent will not be deemed underemployed if the parent is caring for a child under 6 months of age.'
If you do not earn much
'There is a rebuttable presumption that a minimum amount of support is at least $50.00 per month per child.' For incomes below $800 a month the rule tells courts to 'carefully review' the case to set the most support possible 'without denying a parent the means for self-support at a minimum subsistence level.' At the other end, incomes above $440,000 get individualized treatment.
Childcare and health insurance
'The court may order a sharing of reasonable work-related child care costs incurred by either parent in proportion to their Guideline Income,' normally paid directly between the parents. Health insurance 'should be provided by the parent that can get appropriate coverage through an employer at the lower cost,' and uncovered health expenses are 'shared between the parents based on their pro rata percentages.' Watch this one: any single course of treatment costing more than $500 'must be approved in advance, in writing, by both parents or by prior court order.'
Private school, special needs, activities
There is no standing private-school line item. For high-income cases the rule tells the court to weigh 'the standard of living the child enjoyed during the marriage,' 'educational needs,' 'special impairment … disability … special education,' 'special ability or talent,' and 'special living conditions.' Otherwise these expenses come in as an adjustment to the guideline amount.
When a judge can depart from the number
'The Guidelines amount can be adjusted if evidence shows that amount to be inappropriate. In such a case the court will set forth on the record the dollar amount of support that the Guidelines would ordinarily calculate and then cite the circumstances justifying departure.'
Two surprises. First, the $500 rule: if your child needs a course of medical or dental treatment that will run over $500 and you have not gotten the other parent's written agreement or a court order first, you may be stuck with the whole bill. Second, Idaho will not order anyone to pay for college, no matter how much the parents earn – if that matters to you, it has to go into your settlement agreement.
Later on
When it ends
The Guidelines apply to 'children under the age of 18 years or children pursuing high school education up to the age of 19 years.'
College and support after 18
The rule is blunt: 'Support for education following high school is not available under these Guidelines.' If you want college costs covered in Idaho, it has to come from an agreement between you and the other parent.
Changing the amount later
'When the amount of child support under these Guidelines changes, it may constitute a substantial and material change of circumstances for granting a motion for modification for child support amount.' Idaho generally requires a substantial and material change in circumstances.
How far back a change can reach
We could not confirm Idaho's rule on how far back a change reaches from an official source, so nothing is stated here. Assume the safe course: file as soon as your circumstances change.
If someone stops paying
We did not confirm Idaho's official enforcement tools – license suspension, interest on arrears – on a state source, so none are stated here.
What we could not confirm
- We could not confirm how far back an Idaho modification can reach, or the state's official enforcement tools. The Idaho Supreme Court's forms site blocked us, though we did reach the rule itself and the two official worksheets.
- 1 official page we tried to read refused automated access. We did not try to get around the block, so some detail above comes from a different official source rather than the one we would have preferred.
Compare all fifty states
The overnight thresholds, the ending ages and the college rules, side by side.
The rest of what we have written about Idaho. Every figure is quoted from Idaho’s own statute or its courts’ own published schedule, and carries the date we last checked it.