Estimate monthly child support payments using your state's actual guideline formula. Income shares, percentage of income, and Melson formula models — free, no signup.
Child support in the United States is not set arbitrarily — every state is required by federal law to use a numeric guideline formula. States use detailed formulas to calculate a baseline support amount, but courts may deviate from this standard when special facts justify a different approach. The overarching goal is to ensure children receive the same proportion of parental income they would have received if the family had remained intact.
According to the National Conference of State Legislatures, child support guidelines in each state follow one of three models: the income shares model, the percentage of income model, and the Melson Formula. Understanding which model your state uses is the essential first step in estimating your obligation.
Both parents' gross incomes are combined. A state-published table shows the basic child support obligation for that income level and number of children. Each parent pays their proportional share based on their percentage of combined income. Parenting time adjustments reduce the non-custodial parent's obligation.
Only the non-custodial parent's income is used. Child support is 20% of net income for one child, 27% for two, 33% for three, and 3% more per additional child. Used in Texas, Wisconsin, Nevada, Illinois, Mississippi, and North Dakota. Simpler to calculate but does not account for the custodial parent's income.
The most complex model. First reserves a self-support amount for each parent, then determines the primary support need for the children, then allocates remaining income proportionally. Used in Delaware, Hawaii, and Montana. Estimates from any calculator should be confirmed against the state's official worksheet.
The baseline formula is only the starting point. Courts in all states consider additional factors that can increase or decrease the guideline amount:
| Factor | Effect on Support | Notes |
|---|---|---|
| Parenting time / overnights | Decreases obligation | Most states reduce support when non-custodial parent has 92+ overnights/year |
| Childcare costs | Increases obligation | Work-related childcare is typically added to the basic obligation and split proportionally |
| Health insurance premiums | Increases obligation | Cost of child's health insurance is added and split between parents |
| Children from other relationships | Decreases obligation | Legal obligations for other children may reduce available income |
| Special needs | Increases obligation | Courts can deviate upward for extraordinary medical, educational, or therapeutic needs |
| Imputed income | Increases obligation | If a parent is voluntarily underemployed, court assigns income based on earning capacity |
The table below shows approximate monthly child support at a $60,000 combined gross annual income ($5,000/month) for one child, with standard visitation (non-custodial parent has approximately 20% of overnights). These are estimates — actual amounts depend on your state's official guideline worksheet.
| State | Model | Est. Monthly Support | Notes |
|---|---|---|---|
| California | Income Shares | $900–$1,100 | High cost of living adjustments common |
| Texas | % of Income | $800–$1,000 | 20% of NCP net income; net ≈ 75% of gross |
| Florida | Income Shares | $700–$900 | Standard parenting time reduction applies |
| New York | Income Shares | $900–$1,200 | 17% of combined income for 1 child guideline |
| Illinois | % of Income | $850–$1,050 | 20% of NCP net income |
| Ohio | Income Shares | $700–$850 | Standard schedule applies |
| Georgia | Income Shares | $650–$850 | Income schedule-based calculation |
| North Carolina | Income Shares | $700–$900 | Pro-rated by income share |
| Virginia | Income Shares | $750–$950 | Standard schedule |
| Wisconsin | % of Income | $750–$950 | 17% of gross income for 1 child |
A child support order is not permanent. Either parent can request a modification when there is a substantial change in circumstances. Most states define substantial change as a 15–20% change in either parent's income, a significant change in the custody arrangement, or a material change in the child's needs.
Job loss, pay cut, or significant income increase are the most common grounds for modification. The change must be involuntary or long-term — a temporary pay cut typically does not qualify.
If the custody or parenting time arrangement changes significantly, support should be recalculated. A parent who gains more overnights typically sees their obligation reduced.
New medical conditions, special education needs, or other extraordinary expenses may justify an upward modification. Emancipation or the child turning 18 triggers downward modification or termination.
Important: Never stop paying child support without a court order, even if you agree verbally with the other parent. Unpaid support accumulates as arrears, accrues interest, and can result in license suspension, wage garnishment, or contempt proceedings. Always get changes approved by the court.
Income shares vs percentage of income vs Melson formula — explained in plain language with worked examples for each model.
Read guide →Complete state-by-state breakdown of which model each state uses, with estimate tables at common income levels.
Read guide →When you can request a modification, what qualifies as a substantial change, and what to expect from the court process.
Read guide →