Child Support Calculator by State

The four child support models used in the U.S.

• Income shares (about 40 states). Both incomes are combined, the state's schedule sets the total amount expected to be spent on the children, and that amount is divided in proportion to each parent's income, then adjusted for overnights.
• Percentage of obligor income (TX, WI, MS, AK, ND, NV). Only the paying parent's income matters. Texas applies 20/25/30/35/40% of net resources up to a statutory cap; Wisconsin applies 17/25/29/31/34% of gross; Nevada uses tiered brackets.
• Melson formula (DE, HI, MT). Each parent keeps a self-support allowance, the children's primary needs are funded next, and a standard-of-living allowance is added from whatever income is left.
• California's algebraic guideline. CS = K x (HN − H% x TN), where timeshare feeds the formula continuously — every overnight moves the number.

Overnights are the variable most parents get wrong

Thresholds differ enormously: Indiana starts crediting parenting time around 52 overnights, Colorado at 93, Maryland at 92, North Carolina at 123, Illinois and Pennsylvania at 146 — while Texas, Georgia, Rhode Island and Washington give no automatic credit at all. In threshold states a handful of nights either way can swing support by hundreds of dollars a month, which is why courts want a documented overnight count rather than a memory of the schedule.

Count yours precisely with the custody percentage calculator, read your state's parenting plan guide for local terminology, split the extras with the expense split calculator, and keep every shared cost documented in the shared expense tracker so the numbers you bring to court are provable.

Guideline model by state

Income-shares states publish a full schedule of basic obligations that varies with income. This tool models the effective rate those schedules produce at typical middle incomes, so results track published worksheets closely but are not a substitute for the official calculation.