Income Shares Model Calculator - How 41 States Calculate Support

The income shares model is the most widely used child support calculation method in the United States, adopted by 41 states. Unlike the percentage of income model, which only considers one parent's income, the income shares model considers both parents' incomes to determine the total child support obligation and then allocates each parent's proportional share.

How the Income Shares Model Works

The income shares model is based on the economic principle that children should receive the same proportion of parental income that they would have received if the family were intact. The calculation follows these steps:

Step 1: Determine Each Parent's Gross Income

Both parents' gross incomes are calculated. Gross income typically includes wages, salaries, commissions, bonuses, self-employment income, investment income, rental income, retirement benefits, and other sources. Some states adjust gross income by deducting certain mandatory obligations such as taxes, Social Security, Medicare, mandatory retirement contributions, union dues, and existing child support or alimony obligations for other families.

Step 2: Calculate Combined Adjusted Income

The parents' adjusted incomes are added together to determine the combined adjusted gross income. This total represents the family's financial capacity to support the child.

Step 3: Look Up the Basic Support Obligation

Each state has a schedule or table that shows the basic child support obligation based on the combined income and the number of children. These tables are developed using economic data about what families at various income levels actually spend on their children. The table provides a single dollar amount representing the total child support obligation for both parents combined.

Step 4: Determine Each Parent's Proportional Share

Each parent's share of the basic support obligation is calculated based on their percentage of the combined income. For example, if Parent A earns $60,000 and Parent B earns $40,000 (combined $100,000), Parent A is responsible for 60% and Parent B for 40% of the basic support obligation.

Step 5: Apply Adjustments

The basic obligation is adjusted for specific child-related expenses:

• Health insurance premiums: The cost of the child's health insurance is added to the basic obligation and allocated proportionally
• Childcare costs: Work-related childcare expenses are added and allocated
• Extraordinary medical expenses: Uninsured medical, dental, and mental health costs
• Extraordinary educational expenses: Private school tuition, special education costs (in some states)
• Parenting time adjustment: Many states reduce the noncustodial parent's obligation when they have significant overnight time (often 90-110+ overnights per year), reflecting the direct costs incurred during parenting time

Step 6: Calculate the Final Support Amount

The noncustodial parent's share, after adjustments, becomes the child support order. The custodial parent's share is presumed to be spent directly on the child through daily care expenses.

Example Calculation

Here is a simplified example of how the income shares model works:

States Using the Income Shares Model

Forty-one states use the income shares model, including Alabama, Arizona, California, Colorado, Connecticut, Florida, Georgia, Idaho, Illinois, Indiana, Iowa, Kansas, Kentucky, Louisiana, Maine, Maryland, Michigan, Minnesota, Missouri, Nebraska, New Hampshire, New Jersey, New Mexico, New York, North Carolina, North Dakota, Ohio, Oklahoma, Oregon, Pennsylvania, Rhode Island, South Carolina, South Dakota, Tennessee, Utah, Vermont, Virginia, Washington, West Virginia, and Wyoming.

Shared Custody Adjustments

Most income shares states adjust the child support calculation when the noncustodial parent has significant parenting time. The threshold varies by state -- commonly 90, 110, or 128 overnights per year. When the threshold is met, the calculation accounts for the fact that the noncustodial parent directly incurs expenses during their parenting time (food, transportation, activities, etc.).

The most common approach is to calculate each parent's support obligation, multiply by their percentage of parenting time, and then offset the obligations. The parent with the larger obligation pays the difference to the other parent. This "cross-credit" approach results in lower support payments in shared custody arrangements.

Imputed Income

When a parent is voluntarily unemployed or underemployed, courts can "impute" income -- calculating support based on what the parent could earn rather than what they actually earn. Factors courts consider include the parent's education, work history, skills, health, age, the local job market, and prior earning history. This prevents parents from avoiding support obligations by deliberately reducing their income.

Deviation from Guidelines

While the income shares model produces a presumptive support amount, courts can deviate from the guidelines when the result would be unjust. Common reasons for deviation include extraordinary medical expenses, travel costs for long-distance parenting time, the child's special needs, existing support obligations for other children, high income (above the schedule maximum), and educational expenses.

Frequently Asked Questions