Modify Child Support — Not Just a Calculator
Skip the scattered calculators. Get a guided, step-by-step child support plan that walks the full lifecycle — from filing to a new order — with a printable takeaway and a gap/eligibility check you can act on. Every figure statute-cited to your state’s guideline.
Full U.S. coverage
Every state + D.C., one hub.
Statute-cited
Each figure links to its state law.
Official schedules
47 states loaded from agency tables.
3 models explained
Income Shares, Percentage & Melson.
Go beyond a basic estimate
Three planning tools that set ChildSupportFig apart — work backwards, model a life change, and compare every state at once.
Reverse calculator
Target a monthly payment → see the income it implies under your state’s guideline.
Open →⇄What-if simulator
Compare two scenarios — a raise, custody change, or added costs — side by side.
Open →≣Cross-state compare
See how the same income produces different obligations across all 50 states + D.C.
Open →20262026 rule changes
Passport revocation for arrears, NY $193k cap, MA $450k, WA $50k — dated and sourced.
Open →⇅Modification check
Do you meet your state’s threshold to change the order? 51-state go/no-go with statutes.
Open →Child support — quick answers
Is this child support calculator free?
Yes. Every state estimator, the reverse calculator, the what-if simulator, and the cross-state comparison are free and ad-supported.
How accurate are the estimates?
States with a verified statutory or agency schedule use real published rates. Other states are clearly labeled “model estimate” and use a reference schedule until verified against the official guideline.
Does child support law differ by state?
Yes. Each state uses one of three models — Income Shares, Percentage of Income, or the Melson Formula — with its own income definition and schedule.
Select your state
Green = official schedule loaded. Red = model estimate pending verification.
How U.S. child support models differ
- Income Shares (41 states + D.C.): both parents’ incomes are combined, matched to a schedule, then split proportionally — plus child-care and health-insurance add-ons and a parenting-time credit. Deep dive →
- Percentage of Income (6 states): a flat or graduated percentage of only the paying parent’s income — the simplest model, shown here with verified statutory rates. Deep dive →
- Melson Formula (3 states): Income Shares plus a self-support reserve and standard-of-living adjustment (Delaware, Hawaii, Montana). Deep dive →
Guides & articles
Plain-English explainers for parents and payers — each links straight to the calculators.
What Is Child Support?
A plain-English primer on what child support is, who pays it, what it covers, and how it differs from other family-law obligations.
The mathHow Is Child Support Calculated?
The three U.S. guideline models explained — Income Shares, Percentage of Income, and the Melson Formula — and the inputs that move the number.
Model deep-diveWhat Is the Income Shares Model?
The most common U.S. child-support model, explained: combined income, the basic-obligation schedule, proportional splitting, and add-ons.
Model deep-diveWhat 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.
State resources, on every page
Each state calculator now includes a resources section with how that state calculates support, how to open or modify a case, illustrative examples, frequently asked questions, and direct links to the official statute and child-support agency. Where we are still verifying a section against primary sources, it is clearly marked “coming soon.”
Compare & learn
See how the same income produces different obligations across states on the cross-state comparison tool, browse the full child support by state table, read the model guides, or start with the basics articles.
More planning tools & guides
Deeper tools for specific situations — each grounded in state law and linked from the calculators above.
Income Change Simulator
Model how a raise, job loss, or new child changes your obligation.
High incomeHigh-Income Child Support
Above-guideline caps and deviations (NY, MA, WA and more).
Post-18Child Support After 18
When support continues for college or disability.
Multi-stateInterstate Cases (UIFSA)
Which state decides when parents live in different states.
DeadlinesStatute of Limitations
How long arrears and enforcement actions can last.
WorksheetChild Support Worksheet
A fillable worksheet to organize your own numbers.
MonitorReview Reminder
Set a reminder to revisit your order when life changes.
SourcesCitation Packs
Per-state statute and agency citations in one place.
Hero photo by Cheung Yin on Unsplash.