Child Support Estimate Calculator
Estimate monthly child support obligations using the widely adopted Income Shares Model, which bases support on both parents' combined income and the number of children.
Formula & Methodology
This calculator uses the Income Shares Model — the standard adopted by most U.S. states:
- CAGI = NCP Gross Monthly Income + CP Gross Monthly Income
- BCSO = Interpolated from the Income Shares schedule table based on CAGI and number of children
- TSO = BCSO + Monthly Childcare Costs + Health Insurance Premium
- NCP Income Share = NCP Income ÷ CAGI
- NCP Preliminary Obligation = TSO × NCP Income Share
- Parenting-Time Credit (if NCP parenting days ≥ 73/year):
Credit = (NCP Day Fraction − 0.20) × 1.5 × TSO - Final NCP Obligation = NCP Preliminary Obligation − Parenting-Time Credit (minimum $0)
Assumptions & References
- Uses a representative Income Shares schedule derived from USDHHS guidelines; actual state schedules vary.
- Parenting-time credit applies when the non-custodial parent has 73 or more overnights per year (≥20%).
- The 1.5× multiplier in the parenting-time credit reflects the recognised "two-household" cost increase in shared custody arrangements.
- Gross income is used (before taxes); some states use net income — adjust accordingly.
- Extraordinary expenses (medical, educational, extracurricular) are not included.
- Reference: U.S. Dept. of Health & Human Services, Office of Child Support Services — Essentials for Attorneys in Child Support Enforcement (2023).
- Reference: Williams, R. (1987). Guidelines for Setting Levels of Child Support Orders. Family Law Quarterly.