Indiana's Income Shares Model Explained
Here's something most parents don't realize until they're sitting in court: your child support amount isn't based solely on your income. Indiana combines both parents' earnings and splits the obligation proportionally. That means the other parent's income directly affects how much you pay—or receive.
What is the Income Shares Model? (And Why It Matters to You)
The Income Shares Model is based on a simple premise: children should receive the same proportion of parental income they would have gotten if the parents stayed together. Sounds straightforward, right? But here's where it gets interesting.
Instead of just looking at one parent's paycheck—the old "percentage of obligor income" approach—Indiana adds both parents' incomes together, calculates the total support obligation, then divides it based on each parent's share of the combined income.
Real-world example I see all the time: Parent A makes $75,000. Parent B makes $25,000. The old model would ignore Parent B's income and just hit Parent A with a flat percentage. Indiana's model? It recognizes Parent B can contribute too, so Parent A's payment is lower than it would be under the old system.
The Four Core Principles (That Actually Matter)
- Both incomes count: Whether you're mom or dad, custodial or non-custodial, your income affects the calculation
- Proportional responsibility: If you earn 70% of the combined income, you're responsible for roughly 70% of the support obligation
- Child-centered, not parent-centered: The focus is maintaining what the child would have received in an intact household
- Research-backed percentages: The guideline percentages (14.5% for one child, 21.5% for two) come from economic studies of how intact families actually spend on children
How It Works: Step-by-Step
Example Calculation
Parent A income: $60,000/year ($1,154/week)
Parent B income: $40,000/year ($769/week)
Children: 2
- Combine incomes: $1,154 + $769 = $1,923/week
- Apply percentage: $1,923 × 21.5% (for 2 kids) = $413/week total obligation
- Calculate each parent's share:
- Parent A: 60% of income = $248/week obligation
- Parent B: 40% of income = $165/week obligation
- Determine payment: Custodial parent gets credit for direct care. If Parent B has custody, Parent A pays $248/week to Parent B.
Indiana's Guideline Percentages
| Number of Children | Percentage of Combined Income |
|---|---|
| 1 child | 14.5% |
| 2 children | 21.5% |
| 3 children | 27.5% |
| 4 children | 31.5% |
| 5 children | 34.5% |
| 6+ children | 36% |
Why a Simple Percentage Can Mislead You
Many parents try to estimate support by asking, "What percent of income is child support?" That shortcut can be useful for a rough mental check, but it can be wrong when used as a final answer. Indiana calculations usually require both parents' weekly gross incomes, the number of children, parenting time, healthcare premiums, childcare expenses, and certain deductions.
For example, two parents with the same combined income can have different orders if one parent pays the child's health insurance premium, if work-related childcare is high, or if the paying parent has significant overnight parenting time. The Income Shares Model is meant to allocate the total child-related obligation, not simply punish one parent with a fixed percentage.
How Income Shares Affect the Paying Parent
After combined income is identified, each parent's percentage share matters. If Parent A earns 70% of the combined income and Parent B earns 30%, Parent A is usually responsible for a larger share of the support obligation. But who actually pays depends on the parenting arrangement and which parent is already directly covering expenses.
This is why the same income level can produce different outcomes. If the higher-earning parent also has substantial parenting time, the parenting time credit may reduce the payment. If the lower-earning parent pays childcare or insurance, those costs can increase the amount allocated through the worksheet.
What the Model Does Not Decide
The Income Shares Model does not decide custody, parenting time, or whether either parent is a good parent. It is a financial allocation method. Parenting time orders and custody decisions are separate legal issues, even though the number of overnights can affect the worksheet.
The model also does not automatically handle every unusual case. Self-employment, voluntary unemployment, fluctuating income, split custody, children from other relationships, and extraordinary expenses may require more detailed review. In those situations, the official calculator and a qualified attorney are safer than a simple online estimate.
How to Use This Model Safely
Use the model to understand the logic of the calculation, then use official tools for numbers that matter. A practical workflow is:
- Gather current weekly gross income for both parents.
- List health insurance premiums for the child only.
- List work-related childcare costs with provider documentation.
- Count annual overnights carefully, not just weekends or visits.
- Run an educational estimate, then verify with the official Indiana calculator before filing.
Other State Models
Not all states use the Income Shares Model. Here are the main approaches:
1. Income Shares Model (Indiana + 40 states)
Considers both parents' incomes, divides obligation proportionally.
States: Indiana, Ohio, Michigan, Illinois, most others
2. Percentage of Income Model
Only looks at non-custodial parent's income, applies flat percentage.
States: Wisconsin, Texas, Arkansas
Example: In Wisconsin, 17% of non-custodial parent's income for 1 child, regardless of other parent's earnings.
3. Melson Formula
Complex model that ensures both parents meet basic needs first, then allocates support.
States: Delaware, Hawaii, Montana
Why Indiana Uses This Model
Indiana adopted the Income Shares Model because it:
- Is fairer: Accounts for both parents' ability to pay
- Reflects reality: Based on how intact families spend on children
- Adjusts automatically: If both parents earn well, both contribute more
- Prevents inequities: A wealthy custodial parent doesn't get the same support as a poor one