Understanding the Percentage of Income Model
Six states use the Percentage of Income model for child support: Alaska, Mississippi, Nevada, North Dakota, Texas, and Wisconsin. If you live in one of these states, this calculator applies to you. The model works differently from the Income Shares formula used by most states — and understanding the difference helps you interpret your result correctly.
The core distinction is this: the Percentage of Income model bases the monthly obligation on the paying parent's income alone. The receiving parent's income is not part of the base formula. A fixed percentage is applied to the paying parent's income based on the number of children. The result is the monthly obligation.
This makes the formula simpler than Income Shares — but it also means the calculation does not automatically adjust for large income differences between the two parents the way an Income Shares formula does.
The Mathematical Formula
The calculation follows two steps.
Step one is determining the paying parent's income figure. This varies by state. Texas uses net resources — gross income minus taxes, FICA, and the children's health insurance premiums. Mississippi uses adjusted gross income — gross income minus federal taxes, state taxes, and FICA. Nevada uses raw gross income with no deductions. Wisconsin uses gross income with limited deductions for prior support orders. The specific income definition matters significantly. Entering the wrong type of income produces an inaccurate result.
Step two is multiplying that income figure by the applicable percentage based on the number of children. The percentages differ by state but follow a consistent structure — they increase with each additional child and flatten out at higher child counts because each additional child costs proportionally less than the first.
Nevada's tiered percentages (NAC 425.140) on the first $6,000 of monthly gross income are 16 percent for one child, 22 percent for two, 26 percent for three, and 28 percent for four, with lower rates on income above $6,000 and above $10,000. Alaska applies 20 percent for one child, 27 percent for two, 33 percent for three, and 3 percent more for each additional child to adjusted net income. Wisconsin uses 17 percent for one child, 25 percent for two, 29 percent for three, 31 percent for four, and 34 percent for five or more. Mississippi uses 14 percent for one child, 20 percent for two, 22 percent for three, 24 percent for four, and 26 percent for five or more. North Dakota uses a published schedule based on the obligor's net income; at around $4,000 net per month it works out to roughly 19 percent for one child and 28 percent for two.
Step-by-Step Guide to Using This Calculator
Step 1 — Identify which income figure your state uses. Texas requires net resources. Mississippi requires adjusted gross income after taxes. Nevada, Wisconsin, and most others use gross income. Entering the wrong income type will produce a misleading result. Review your state's definition before entering a number.
Step 2 — Calculate your income figure accurately. For gross income states, use income before taxes and before any deductions. Include wages, self-employment profit after business expenses, rental income, and any other regular source. For net income or adjusted gross income states, work through the specific deductions your state requires.
Step 3 — Select the number of children covered by this order. The percentage is determined entirely by this number in the Percentage of Income model.
Step 4 — Review the state-specific cap if applicable. Texas applies a monthly cap on net resources above which the standard percentage does not automatically apply. Courts have discretion above that cap. If your income is high, note whether the cap affects your result.
Step 5 — Add healthcare and childcare costs. Most Percentage of Income states add the children's health insurance premium on top of the base percentage result. Work-related childcare is often allocated separately.
How to Read Your Results
The results show the paying parent's income figure, the applicable percentage, the base monthly obligation, any add-on costs, and the final monthly total. The receiving parent's income does not appear in the base calculation — that is by design in this model.
If both parents earn similar incomes, the result may feel asymmetric compared to what an Income Shares state would produce. This is a known characteristic of the Percentage of Income approach. The formula prioritizes simplicity and the paying parent's capacity over proportional sharing between both parents.
Parenting Time in Percentage of Income States
Most Percentage of Income states do not include an automatic parenting time credit in the base formula. Texas, for example, builds its formula around a standard possession order assumption and does not reduce the percentage for standard visitation time.
Some states — particularly Wisconsin — have a specific shared placement adjustment when each parent has at least 25 percent of physical placement time. That adjustment uses a different calculation method and produces a meaningfully different result than the standard percentage formula.
If you have significant parenting time and believe the standard percentage does not reflect your actual financial contribution, a deviation based on parenting time is possible in most states — but it requires a court finding. Talk to a family law attorney about whether a deviation request makes sense for your situation.
When Results Differ from Expectations
If your result looks significantly different from what you expected, check which income figure you entered. The most common error is entering gross income in a net income state or entering take-home pay in a gross income state. A $1,000 difference in the income figure produces a $200 difference in the monthly obligation for a two-child order at the 25 percent tier.
Submit your numbers for a free review by a licensed family law attorney in your state.