Child Support Guides
Understand the math before you estimate — the three U.S. models and the inputs that move the number.
Photo by Tingey Injury Law Firm on Unsplash.
1. The three guideline models
Every U.S. state uses one of three structures (or a hybrid). Knowing which one applies to you explains why a neighbor in another state can owe a very different amount on the same paycheck.
- Percentage of Income (6 states): a flat or graduated percentage of only the paying parent’s income. Simplest and most predictable — Texas, Wisconsin, Alaska, Mississippi, Nevada, North Dakota.
- Income Shares (41 states + D.C.): both parents’ incomes are added, matched to a schedule of “basic” support, then each parent pays their proportional share. Child care and health insurance are added on top, and significant parenting time can trigger a credit.
- Melson Formula (Delaware, Hawaii, Montana): Income Shares plus a protected self-support reserve for each parent and a standard-of-living adjustment for the child.
Income Shares — the model behind “income shares” (41 states + D.C.)
If you searched for income shares, this is the model most U.S. states use to set child support. Both parents’ incomes are combined into one shared-income pool, matched to a schedule of basic support obligations, then each parent pays their proportional share. Child care and health insurance are typically added on top, and roughly 40%+ parenting-time overnights can trigger a credit that lowers the base amount.
Frequently asked questions about Income Shares
- Which states use Income Shares? 41 states plus D.C. The rest use Percentage of Income (6 states) or the Melson Formula (Delaware, Hawaii, Montana).
- Does both parents’ income count? Yes — unlike flat percentage-of-income states, Income Shares pools both incomes before splitting the obligation by each parent’s share.
- Where do I calculate my own number? Use your state page (start from the state comparison) and the calculator, which applies your state’s exact schedule.
2. What “income” actually means
States differ on the basis: some use gross (pre-tax), some net (after taxes and mandatory deductions), and some adjusted gross. This single choice can swing the obligation by 20–30%. Always check your state’s basis before comparing figures, and use the basis our per-state calculator asks for.
3. The inputs that move the number
- Number of children — obligations rise, but usually at a decreasing rate.
- Parenting time (overnights) — in Income Shares states, ~40%+ overnights often reduces the base through a credit.
- Child care & health insurance — typically split in proportion to income, on top of the basic obligation.
- Existing orders / other children — many states deduct support already paid for other households.
Our calculators let you enter these where the model uses them. Start with your state page, then use the comparison tool to see how a move across state lines would change the outcome.
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).
