Child Support Calculations in Iowa

Iowa calculates child support using a pure Income Shares model under the Iowa Supreme Court's Chapter 9 Child Support Guidelines. This approach ensures children receive the same proportion of parental income they would have enjoyed had the family remained intact. Whether you're navigating an uncontested or contested divorce, understanding Iowa's 128-overnight threshold and unique 1.5x joint custody multiplier is essential for accurate calculations.

The Pure Income Shares Model

Iowa adopted its "pure" income shares guideline model in 2009, as codified in Iowa Court Rules Chapter 9. The model combines both parents' adjusted net incomes to determine a base child support obligation that reflects what intact families at similar income levels typically spend on children.

The Schedule of Basic Support Obligations appears in Rule 9.26, with worksheets in Rule 9.27 and computation methods in Rule 9.14. The current schedule took effect January 1, 2022 (by court order dated September 3, 2021), though updates effective January 1, 2026 have been ordered.

Calculating Net Monthly Income

Iowa uses net monthly income rather than gross income for support calculations. Gross income includes wages, salaries, commissions, regular bonuses, self-employment income (gross receipts minus reasonable business expenses), and spousal support received. It excludes public assistance payments, the Earned Income Tax Credit, and child support received for other children.

Allowable deductions to reach net income include:

• Federal and state income taxes (computed by guideline method)
• Social Security and Medicare (FICA)
• Mandatory pension contributions and union dues
• Support obligations actually paid under other orders
• Qualified Additional Dependent Deduction (QADD)
• Actual child-care expenses (if no variance is ordered)

Qualified Additional Dependent Deduction (QADD)

Parents with legal obligations to children from other relationships may claim QADD. The deduction equals a percentage of gross income (8% for one child, 12% for two, 14% for three, 15% for four, 16% for five or more), subject to dollar caps ($800 to $1,600). QADD cannot be used for children already subject to a separate support order.

The Support Schedule and Income Thresholds

Rule 9.26 establishes Iowa's support schedule with important income-based distinctions:

Low-Income Areas (Shaded Bands)

Area A ($0-$1,100 net): Uses only the noncustodial parent's income for calculation, protecting low-income obligors from impossible payment burdens.

Area B (varies by children): Performs two calculations—both the Area A method and the standard combined-income approach—and uses the lower result. For one child, Area B spans approximately $1,101-$1,600 net.

Area C (standard): Uses combined net incomes following the standard income shares methodology.

Income Cap and Minimums

The combined net monthly income cap is $25,000. For incomes above this threshold, support amounts are within the court's discretion but cannot be less than the amount at the $25,000 level. Minimum orders appear at the lowest schedule bands: $50 for one child, $75 for two children, $100 for three or more.

Parenting Time Adjustments

Iowa provides specific adjustments based on custody arrangements and overnight counts.

Extraordinary Visitation Credit (128+ Overnights)

When the noncustodial parent has court-ordered overnights exceeding 127 per year but the case is not joint physical care, Iowa applies tiered percentage credits:

• 128-147 overnights: 15% credit
• 148-166 overnights: 20% credit
• 167+ overnights: 25% credit (but less than joint physical care)

The credit is applied to the noncustodial parent's basic support obligation before health insurance adjustments. Importantly, the credit cannot reduce support below the guideline minimums ($50/$75/$100).

Joint Physical Care (1.5x Multiplier)

When courts award joint physical care (even without mathematically equal time), Iowa applies a unique formula under Rule 9.14(3):

1. Compute each parent's proportional share of the basic obligation using combined net income
2. Multiply each share by 1.5 (to reflect duplicated fixed household costs in two homes)
3. Multiply that result by 0.5 (for 50% time in each home)
4. Adjust for children's health insurance costs
5. Offset the two obligations—the parent with the higher amount pays the net difference

Split or Divided Physical Care

When at least one child resides with each parent, Iowa computes each parent's obligation for the children in the other's care and offsets the amounts. The parent with the higher obligation pays the net difference.

Medical Support and Childcare

Medical support provisions are mandatory in all Iowa child support orders.

Health Insurance

Rule 9.12(4)'s Medical Support Table determines "reasonable cost" based on a percentage of gross income—generally 5% outside the shaded low-income areas, with 1-5% in shaded bands. If reasonably priced insurance is available, it must be ordered. If not, courts order cash medical support using the same table percentages.

Uncovered Medical Expenses

For non-joint custody cases, the custodial parent pays the first $250 per child per calendar year (capped at $800 per family per year) of uncovered medical expenses. Amounts above that are shared proportionally to income. In joint physical care, uncovered medical is split proportionally from the first dollar with no threshold.

Childcare Expenses

Because childcare costs are not embedded in the schedule's economic data, Rule 9.11A provides for an upward variance based on necessary work, education, or job-search childcare costs. The variance must specify the amount and end date. This approach applies only in primary-care cases; joint physical care allocates childcare under Rule 9.14(3).

Iowa Child Support Calculator

Use our calculator to estimate your potential child support obligation under Iowa's guidelines. Enter both parents' income information and custody arrangement to see how the rules apply to your situation.

For official calculations, use the Iowa Child Support Estimator from the Iowa Department of Health and Human Services.

Modifying Child Support Orders

Iowa provides both judicial and administrative pathways for modification.

Judicial Modification (10% Threshold)

Under Iowa Code § 598.21C, a support amount that varies by 10% or more from the current guideline amount is, by itself, a substantial change in circumstances justifying modification.

Administrative Review (20% Threshold)

Iowa Child Support Services (CSS) offers administrative review every 24 months. CSS proceeds when: (1) the current order varies from the guideline amount by more than 20%, and (2) the change has lasted at least 3 months and is expected to continue for 3 more months.

Review your Iowa divorce timeline to understand when modification opportunities arise.

Enforcement and Arrears

Iowa employs comprehensive enforcement mechanisms for child support compliance:

• Immediate income withholding: Automatic wage garnishment through employers (must remit within 7 business days)
• State setoff: Tax refunds, lottery and casino winnings, and vendor payments intercepted
• Federal tax refund offset: Through the Treasury Offset Program
• Administrative bank levies: When one month's delinquency exists
• License sanctions: Suspension of driver's, professional, and recreational licenses
• Contempt proceedings: Court-ordered compliance with potential jail time

Interest on Arrears

Past-due periodic support accrues interest at 10% per year, beginning 30 days after a payment's due date. CSS may waive interest to facilitate collection under Iowa Code § 252C.6.

Duration of Child Support

Iowa child support continues until the child turns 18 years old. If the child is engaged full-time in completing high school graduation or equivalency requirements with a reasonable expectation of completion before turning 19, support continues until graduation or age 19, whichever occurs first.

Courts may order support for a child of any age who is dependent because of a physical or mental disability. Iowa also provides for discretionary post-secondary education subsidies under Iowa Code § 598.21F, though this is separate from standard guideline support.

Property Division and Support Interplay

Child support calculations interact with property division decisions. Understanding Iowa's marital property division rules helps you see the complete financial picture. Property settlements may affect income available for support, and asset division can influence each party's financial circumstances post-divorce.

Frequently Asked Questions

What is the 128-overnight threshold in Iowa? When a noncustodial parent has 128 or more court-ordered overnights annually (but not joint physical care), they qualify for an extraordinary visitation credit of 15%, 20%, or 25% depending on the total overnight count.

How does the 1.5 multiplier work in joint custody? Iowa multiplies each parent's proportional share by 1.5 to account for duplicated fixed household costs when maintaining two homes, then multiplies by 0.5 for equal time-sharing before offsetting the two amounts.

What is Iowa's income cap for child support? The combined net monthly income cap is $25,000. Above this level, courts have discretion but cannot set support below the $25,000 schedule amount.

How much interest accrues on unpaid child support in Iowa? Iowa charges 10% annual interest on past-due support, beginning 30 days after each payment's due date.

When can I modify my Iowa child support order? Judicially, when current support differs by 10% or more from the guideline amount. Administratively through CSS, every 24 months when the difference exceeds 20%.

What is the minimum child support in Iowa? Schedule minimums are $50 for one child, $75 for two children, and $100 for three or more children. These minimums apply even after extraordinary visitation credits.