Child support is one of the most important financial agreements divorcing parents make. It’s also one that many parents don’t fully understand until they’re in the middle of it. Illinois doesn’t leave this to negotiation alone. The state uses a specific formula, and knowing how it works helps parents reach agreements that are grounded in what the law actually requires rather than what one party thinks sounds fair.
Illinois Uses the Income Shares Model
Illinois moved to an income shares model for child support in 2017. Under this approach, the court looks at what both parents earn combined and estimates how much that household would have spent on the children if the family had stayed together. That estimated amount becomes the baseline for support.
The calculation is governed by 750 ILCS 5/505, which outlines how support is determined and what factors the court considers. The Illinois Department of Healthcare and Family Services publishes the income shares schedule that translates combined parental income into a basic support obligation.
Each parent’s share of that obligation is then allocated proportionally based on their share of the combined income. If one parent earns 60% of the combined income, they’re generally responsible for 60% of the basic support obligation. The residential parent is assumed to be spending their share directly on the children through day-to-day expenses.
What Income Means for the Calculation
Income for child support purposes in Illinois is broadly defined. It includes:
- Wages, salary, and overtime
- Self-employment income
- Commissions and bonuses
- Rental income
- Social Security and disability benefits
- Pension and retirement distributions
- Unemployment compensation
Both parents’ gross incomes go into the formula before deductions, with certain adjustments allowed for things like existing child support obligations from other relationships and the cost of health insurance premiums for the children.
Self-employed parents require closer attention because their reported income may not reflect their actual earnings. Illinois courts can impute income when a parent is voluntarily underemployed or when business expenses are used to obscure available income. In an agreed divorce, both parents have an incentive to be honest about earnings because the resulting agreement needs to hold up over time.
What Can Be Added on Top of Basic Support
The basic child support obligation covers core living expenses, but Illinois allows for additional costs to be allocated between parents separately. These typically include:
- Health insurance premiums for the children, split proportionally or as agreed
- Uncovered medical, dental, and vision expenses
- Work-related childcare costs
- Extracurricular activity expenses, if agreed upon
How these additional expenses get handled is something parents can negotiate and document in their divorce agreement. Having clear language about who pays what, when, and how reimbursement works prevents disputes down the road.
A Belleville family lawyer helps parents draft child support provisions that are accurate under the Illinois formula and specific enough to avoid ambiguity when real-life situations arise.
How Parenting Time Affects the Calculation
Parenting time allocation affects child support. When both parents have significant parenting time, Illinois applies what’s called the shared physical care calculation. If each parent has the children at least 146 overnights per year, the formula adjusts to reflect that both parents are bearing direct costs during their respective parenting time.
The adjustment reduces the support obligation for the higher-earning parent when parenting time is more evenly split. This is worth understanding before finalizing a parenting plan because the time allocation and the support calculation are interconnected.
Why Getting This Right in an Agreed Divorce Matters
In a contested divorce, a judge determines support based on the formula. In an uncontested divorce, the parents, based on the formula and calculations, agree on an amount and document it in the parenting allocation agreement. That agreed amount still needs to be consistent with what the formula produces. Illinois courts won’t approve a child support agreement that deviates significantly from the statutory guidelines without a specific explanation in the record.
This is one reason why having accurate income figures and understanding the formula before drafting the agreement matters so much. An agreement built on incorrect numbers, or one that doesn’t reflect the actual parenting time arrangement, creates problems at approval and potentially long after.
Flat Fee Divorce Solutions helps Belleville area parents work through the child support calculation and document their agreements accurately under Illinois law. If you and your co-parent have reached your agreements and are ready to move forward, reach out to a Belleville family lawyer to get the process started.
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