Iowa uses an income shares model with a Schedule of Basic Support Obligations (Rule 9.26). Net monthly income is computed under Rule 9.5 (gross minus federal tax, Iowa flat 3.8% state tax, FICA, health insurance, mandatory retirement, prior child support). An extraordinary-visitation credit applies for substantial overnights.
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Iowa calculates child support using the Income shares model established under Iowa Court Rules Chapter 9. This is a statutory formula that leaves limited room for judicial discretion on the base calculation amount, ensuring consistency and predictability for families across the state.
Basic obligation from Rule 9.26 schedule based on combined net monthly income and children. Each parent's share = pro rata. Extraordinary-visitation credit for 128+ overnights.
The calculation begins with determining each parent's net disposable income, which includes virtually all sources of income minus taxes, mandatory payroll deductions, and certain hardship deductions. The court then applies the statutory formula using the time each parent has primary physical responsibility for the children and the applicable income allocation brackets.
Beyond the base formula amount, Iowarequires additional contributions for mandatory add-on expenses. These typically include childcare costs necessary for the custodial parent's employment or education, uninsured healthcare expenses for the children, and in some cases, educational and travel costs. These add-ons are split between parents in proportion to their respective incomes.
Primary statute: Iowa Court Rules Chapter 9
Rule 9.26 Schedule of Basic Support Obligations (updated January 1, 2026).
Net income per Rule 9.5: gross minus taxes, FICA, health insurance, mandatory retirement, prior obligations.
Extraordinary-visitation credit (Rule 9.9): 128 overnights = 15%, 148 = 20%, 166 = 25%; 183+ = shared physical care offset.
2026 update raised obligations by average 7.6%/10.5%/11.6% for 1/2/3 children.
Add-ons: childcare and child health insurance (Rule 9.11A).
Iowa flat 3.8% state tax (effective 2025+) simplifies net income calculation.
Retirement income fully exempt from Iowa state tax (pensions, Social Security, IRA, 401(k), military retirement) since 2023.
Rule 9.26 schedule updated January 1, 2026 by Iowa Supreme Court order (Sept 29, 2025). Obligations raised by average 7.6–11.6%.
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Residency Requirement
1 year residency (Iowa Code §598.5)
Mandatory Waiting Period
90-day waiting period from service (§598.19, waivable for extraordinary circumstances)
No-Fault Ground
Irretrievable breakdown (§598.17) — no-fault only
State Income Tax
Flat 3.8% (effective 2025+, Iowa SF 2442). Retirement income fully exempt since 2023.
Iowa uses the Income shares model under Iowa Court Rules Chapter 9. Iowa uses an income shares model with a Schedule of Basic Support Obligations (Rule 9.26). Net monthly income is computed under Rule 9.5 (gross minus federal tax, Iowa flat 3.8% state tax, FICA, health insurance, mandatory retirement, prior child support). An extraordinary-visitation credit applies for substantial overnights.
Key factors include both parents' income, the number of children, custodial time share, mandatory add-on expenses (childcare, health insurance), and any applicable deductions. Rule 9.26 Schedule of Basic Support Obligations (updated January 1, 2026).
Yes. Either parent can request a modification if there has been a material change in circumstances, such as a significant change in income, custody arrangements, or the needs of the child. The court will recalculate support using the same statutory formula.
Basic obligation from Rule 9.26 schedule based on combined net monthly income and children. Each parent's share = pro rata. Extraordinary-visitation credit for 128+ overnights.
Get a personalized child support calculation based on Iowa's actual statutory formula.
Start My Free IowaEstimate →This tool provides educational estimates based on Iowa family law and does not constitute legal advice. Child support calculations are approximations of the statutory formula and may differ from court-ordered amounts. Consult a licensed Iowa family law attorney before making decisions. Primary statute: Iowa Court Rules Chapter 9.