Illinois does not set a fixed dollar amount for child support — the court calculates it based on both parents' income, custody arrangement, and other factors specific to your case.
There is no standard payment like "$500 per child" in Illinois. Instead, the state uses an income shares model, which means the court looks at what both parents earn, determines what percentage of their combined income should go toward the children, and then divides that obligation between them based on custody time and who earns more.
The calculation starts with net monthly income for each parent — wages after taxes, Social Security, and certain deductions. The court then applies a percentage based on how many children need support. For two children, the guideline percentage is roughly 32 percent of combined net income, though this can shift based on custody split and other circumstances.
Key Takeaways
- Illinois uses combined parental income and a percentage formula, not a fixed amount per child, so two families with the same number of children will have different support orders.
- The guideline percentage for two children is approximately 32 percent of combined net monthly income, divided between parents based on their individual earnings and custody time.
- Income includes wages, self-employment earnings, bonuses, and certain benefits; the court subtracts taxes and specific deductions before calculating the percentage.
- A parent with primary custody typically receives support from the other parent, but if custody is split roughly equally, the higher earner usually pays the lower earner.
- The court can deviate from the guideline amount if circumstances like high income, low income, or significant parenting time differences apply.
How the Illinois Income Shares Formula Works
The calculation has three main steps. First, both parents report their net monthly income. This includes salary, wages, bonuses, self-employment income, rental income, and certain government benefits. It excludes child support already being paid for other children, spousal support paid, and specific tax deductions.
Second, the court adds both parents' net incomes together and applies the guideline percentage. For two children, that percentage is 32 percent. So if Parent A earns $3,000 per month and Parent B earns $2,000 per month, the combined income is $5,000. Thirty-two percent of $5,000 is $1,600 — that is the total child support obligation for both children.
Third, the court divides that $1,600 between the parents based on their share of income and custody time. Parent A earns 60 percent of the combined income ($3,000 ÷ $5,000), so Parent A is responsible for 60 percent of the $1,600 obligation, which is $960. Parent B is responsible for 40 percent, which is $640. If Parent B has primary custody, Parent A pays $960 per month.
Income Limits and High-Income Cases
Illinois sets a cap on guideline income — the formula applies only to combined income up to a certain level. That cap changes yearly and is adjusted for inflation. Once combined income exceeds the cap, the court has discretion to apply the percentage to the excess income or to order a different amount based on the children's actual needs and the parents' standard of living.
This means a parent earning $150,000 per year will not have their support calculated the same way as a parent earning $50,000. The court looks at factors like the children's private school costs, extracurricular activities, and whether the higher-earning parent has historically provided a certain lifestyle.
Similarly, if both parents earn very little, the court may order less than the guideline percentage or may consider other resources like housing provided by a parent or family support.
Custody Time and Support Calculations
The percentage of time each parent spends with the children affects the support order. If one parent has the children 80 percent of the time and the other has them 20 percent, the parent with less time typically pays support to the parent with more time.
If custody is split more evenly — say, 50-50 — the higher earner usually still pays the lower earner, but the amount may be reduced because both parents are sharing day-to-day expenses. The court calculates what each parent's share of the obligation would be, then the higher earner pays the difference to the lower earner.
For example, if the total obligation is $1,600 and Parent A earns 60 percent of income, Parent A owes $960. Parent B owes $640. In a 50-50 custody split, Parent A might pay Parent B $160 per month (the difference) rather than the full $960, because both parents are covering direct costs when the children are with them.
What Income Counts and What Does Not
The court includes wages, salary, bonuses, commissions, self-employment income, rental income, interest and dividend income, and certain government benefits like unemployment or disability. It also includes income from a new spouse or partner if that person lives in the home and contributes to household expenses — though this is applied carefully and is often contested.
The court does not count child support received for other children, spousal support received, public assistance like TANF or SNAP, or the value of food stamps. It also excludes certain tax deductions and work-related expenses.
If a parent is voluntarily unemployed or underemployed — meaning they could earn more but choose not to — the court may impute income, or assign an income level based on their education, work history, and job market. This prevents a parent from avoiding support by quitting their job.
Deviations from the Guideline Amount
The guideline percentage is a starting point, not a ceiling. Illinois law lists reasons a court can order more or less than the guideline amount. These include the financial resources of both parents, the standard of living the children would have had if the parents had remained together, the non-monetary contributions each parent makes (like childcare or household management), and any special needs of the children.
A court might order more than the guideline if one parent has significantly higher income and the children have special needs or attend private school. A court might order less if one parent has very limited income or if both parents share custody nearly equally and both cover substantial direct expenses.
Any deviation must be documented in writing, with the court explaining why the guideline amount is not appropriate. This is important because either parent can later ask the court to reconsider if circumstances change significantly.
How to Find Out Your Specific Amount
You cannot calculate your exact support obligation without knowing both parents' actual net income, custody arrangement, and any special circumstances. If you are in a court case, the other parent or their attorney will file an Income and Expense Statement with the court, and you will file one too. These documents show all income sources and deductions.
If you are trying to estimate before filing, you can use the Illinois Department of Human Services child support calculator, which is available online. You will need recent pay stubs or tax returns for both parents and an estimate of custody time. The calculator gives a rough guideline amount but is not a substitute for a court order.
If you are already receiving or paying support, your order is in a court document called a Judgment for Child Support or Child Support Order. That document shows the exact monthly amount, when it is due, and how it should be paid.
Frequently Asked Questions
Does child support change if one parent loses their job?
Yes, but only if the job loss is involuntary and the parent cannot find comparable work. A parent who is laid off can ask the court to modify the order. The court will look at unemployment benefits, job search efforts, and whether the parent is underemployed. A parent who quits voluntarily usually cannot reduce support, and the court may impute income based on their earning capacity.
What if one parent has a second job or gets a raise?
The increased income is counted in the next support calculation. Either parent can ask the court to modify the order if income has changed by 20 percent or more since the last order. You will need to file a motion and provide recent pay stubs or tax returns showing the new income.
Does the guideline percentage change if one parent remarries?
No. A new spouse's income is not counted in the child support calculation unless they live in the home and contribute to household expenses, and even then it is applied cautiously. The obligation is based on the two biological or adoptive parents' income only.
Can the court order more than the guideline amount for two children?
Yes. If the children have special needs, attend private school, or the higher-earning parent has a much higher standard of living, the court can order above the guideline percentage. The court must document its reasons in writing.
What happens if the paying parent's income is very low?
The court can order less than the guideline amount or may order a minimal payment. However, if the parent is voluntarily underemployed, the court may impute income based on what they could earn. The court also considers whether the parent is receiving public assistance or has other dependents.