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Model deep-dive

What Is the Percentage of Income Model?

The simplest U.S. model: a flat or graduated percentage of the paying parent’s income. How the six states apply it.

Last updated: 2026-08-09

Six states ignore the other parent’s income entirely and apply a percentage of the paying parent’s income. This makes the result predictable but less sensitive to the recipient parent’s means.

Flat percentage states

Graduated schedule state

North Dakota uses a graduated schedule on net income (with a self-support reserve and an aggregate cap), and Nevada applies 18–37% of gross income with a $100/month floor and a joint-custody credit. See Nevada · See North Dakota

Because these states use only the obligor’s income, the calculator needs just one income field. Open Texas to see it in action.
Is a flat percentage fairer or simpler?
Simpler and highly predictable, but it does not account for the receiving parent’s ability to contribute the way Income Shares does.
This article is general education, not legal or tax advice. For your exact number, open your state calculator.
Not legal or financial advice. This estimate follows the state’s statutory guideline formula but cannot capture every factor a court considers (health insurance, childcare, prior orders, deviations, imputed income).