Table of Contents
The Three Child Support Calculation Models
Every state in the United States uses one of three basic models to calculate child support. Understanding which model your state uses is essential because the same family situation can produce significantly different support amounts under different models.
Income Shares (~41 states)
Most common. Considers both parents' incomes. Based on the principle that children should receive the same proportion of parental income they would receive if parents lived together.
Percentage of Income (~6 states)
Simplest model. Applies a fixed percentage to the non-custodial parent's income only. Number of children determines the percentage.
Melson Formula (3 states)
Most complex. Enhanced income shares with self-support reserves and standard of living adjustments. Used by Delaware, Hawaii, and Montana.
Percentage of Income Model
The Percentage model is straightforward: apply a fixed percentage to the non-custodial parent's income based on the number of children. The custodial parent's income is generally not considered.
Percentage varies by state and number of children
| Children | Texas (Net) | Wisconsin (Gross) | Mississippi (Adj.) | Nevada (Gross) |
|---|---|---|---|---|
| 1 | 20% | 17% | 14% | 18% |
| 2 | 25% | 25% | 20% | 25% |
| 3 | 30% | 29% | 22% | 29% |
| 4 | 35% | 31% | 24% | 31% |
| 5+ | 40% | 34% | 26% | 33% |
Melson Formula — Delaware, Hawaii, Montana
The Melson Formula (named after Judge Elwood F. Melson Jr. of Delaware) is the most sophisticated model. It adds two important concepts:
- Self-support reserve — Each parent gets to keep enough income for basic survival (approximately $1,000-$1,300/month, depending on the state). This prevents support orders that push the paying parent below the poverty line.
- Standard of Living Adjustment (SOLA) — When parents earn above the basic needs threshold, a percentage of the excess is added to the child support obligation. This ensures children benefit from higher parental income.
The Melson Formula generally produces higher support amounts for high-income families and lower amounts for low-income families compared to standard Income Shares.
Which Model Does Your State Use?
| Model | States |
|---|---|
| Income Shares | AL, AK, AZ, AR, CA, CO, CT, FL, GA, ID, IL, IN, IA, KS, KY, LA, ME, MD, MA, MI, MN, MO, NE, NH, NJ, NM, NY, NC, OH, OK, OR, PA, RI, SC, SD, TN, UT, VT, VA, WA, WV, WI*, WY |
| Percentage of Income | MS, NV, ND, TX, WI* |
| Melson Formula | DE, HI, MT |
| Hybrid | DC (income shares with percentage elements) |
*Wisconsin uses a percentage model for sole custody and an income shares approach for shared custody. Some states blend elements of multiple models.
Example: Same Family, Different States
Consider a family where Parent A earns $6,000/month gross and Parent B earns $3,000/month gross, with 1 child and sole custody to Parent B:
| State | Model | Estimated Monthly Support | Notes |
|---|---|---|---|
| Virginia | Income Shares | ~$570 | 66.7% of ~$856 obligation |
| Texas | Percentage | ~$800 | 20% of ~$4,000 net income |
| California | Income Shares | ~$620 | Algebraic formula with time-share |
| Delaware | Melson | ~$540 | After self-support reserve + SOLA |
| New York | Income Shares | ~$635 | 17% of combined up to cap for 1 child |
The same family sees a range of roughly $540 to $800/month depending on the state — a 48% difference between the lowest and highest amounts.
Frequently Asked Questions
The three models are: (1) Income Shares (used by ~41 states) - considers both parents' incomes and allocates support proportionally, (2) Percentage of Income (used by ~6 states) - applies a fixed percentage to the non-custodial parent's income only, and (3) Melson Formula (used by 3 states: Delaware, Hawaii, Montana) - a more complex variation of income shares with self-support reserves.
Texas, Wisconsin, Mississippi, Nevada, and North Dakota primarily use the Percentage of Income model. This model is simpler: it applies a fixed percentage to the non-custodial parent's income based on the number of children (e.g., Texas: 20% for 1 child, 25% for 2 children). The custodial parent's income is generally not considered.
The Income Shares model combines both parents' incomes, looks up the total child support obligation from a guidelines schedule, and allocates the obligation based on each parent's share of combined income. The custodial parent's share is assumed to be spent directly on the child. The non-custodial parent pays their share to the custodial parent.
The Melson Formula (used in Delaware, Hawaii, and Montana) is a sophisticated version of Income Shares that includes a self-support reserve for each parent (minimum needed for basic living expenses), a standard of living adjustment (SOLA) that increases support when parents earn above a threshold, and more detailed treatment of additional expenses.
Yes. Most states modify the standard formula for shared custody arrangements. Common adjustments include multiplying the obligation by a factor (1.4-1.5x) to account for duplicated household costs, then offsetting each parent's adjusted obligation. The higher-earning parent typically still pays, but a reduced amount.
State formulas differ in the income used (gross vs. net), the guidelines schedule amounts, treatment of additional expenses, self-support reserves, shared custody adjustments, and deviation factors. A family earning $100,000 combined could owe anywhere from $700 to $1,200/month for one child depending on the state.