Illinois Child Support Calculator

It depends on both parents’ income, the number of children, and how many nights the children spend with each parent. For example, if you earn $4,333 a month before taxes, the other parent earns $3,000, and the children live mostly with the other parent, you would pay about $699 a month for one child or $1,045 for two.

To build the table, we turn weekly pay into monthly pay (× 52 ÷ 12) and subtract standard taxes with the HFS 2026 tax table, as the calculator above does. The parenting schedule doesn’t change these amounts until each parent has at least 146 overnights a year. Illinois’s schedule of support amounts for both parents together is in the 2026 Income Shares Schedule.

Illinois uses an income shares formula. It turns each parent’s gross income (pay before taxes) into net income, adds the two, and looks up the total on the state’s schedule of what parents usually spend on their children. Each parent pays a share based on their part of the income.

The rules are in 750 ILCS 5/505:

1. Find each parent’s gross income from all sources. Cash assistance (TANF), SSI, food stamps (SNAP), and benefits received for other children don’t count.
2. Turn it into net income with the HFS gross to net income conversion table, which subtracts standard taxes for a single filer. The table assumes the parent with more overnights claims the children on their taxes, so that parent gets a little more net income. A judge can use each parent’s actual taxes instead.
3. Subtract support paid for other children and alimony, if any.
4. Add the two net incomes and look up the schedule amount for the number of children.
5. Split it by income share.
6. Adjust for shared care if each parent has at least 146 overnights a year.
7. Add the children’s health insurance, and any child care a judge orders.

Example

One parent earns $4,000 a month and the other $2,000. With the child living with the lower earner, the HFS tax table gives net incomes of $3,167 and $1,706, and the schedule amount for one child at their combined $4,873 is $1,084. The higher earner has 65% of the net income, so they pay about $704 a month.

Yes, once each parent has at least 146 overnights a year (40% of the time). With fewer overnights, time with the children doesn’t change the amount. With one child and gross incomes of $4,000 and $2,000 a month, the higher earner pays about $704 a month when they have 145 or fewer overnights, $406 with 146, $344 with 160, and $246 with equal time.

With shared care, Illinois multiplies the schedule amount by 1.5. Each parent owes their income share of that larger amount for the time the children spend with the other parent. The parent who owes more pays the difference. See 750 ILCS 5/505(a)(3.8).

Starting January 1, 2027, Public Act 104-0733 starts shared care at 110 overnights each. A parent with 110 to 145 overnights owes 10% more (at 110 nights) down to 2% more (at 140 to 145) than the shared care formula gives, but never more than without shared care. The calculator above uses the rule in effect now.

A judge can order both parents to share reasonable child care costs that a parent has so they can work, look for work, or go to school or training. The cost is split by each parent’s share of the combined net income and added on top of basic support.

It can include deposits, before and after school care, and camps when school is out. The value of the federal child care tax credit is subtracted from the cost. Payments go to the other parent or straight to the provider. See 750 ILCS 5/505(a)(3.7).

Every Illinois order must cover the children’s health care. The cost of insuring the children is split by each parent’s share of the income, and the parent who pays the premium gets credit for it. A judge can also split medical bills that insurance doesn’t pay.

• Reasonable cost: covering the children can’t cost the insuring parent more than 5% of their gross income.
• Low income: a parent with net income below 133% of the federal poverty level, or whose children are on Medicaid based on that parent’s income, can’t be ordered to pay for private coverage.
• Everyday costs: basic support already covers some routine out-of-pocket medical costs.

See 750 ILCS 5/505(a)(4).

If the children live with you and you get cash assistance (TANF), you have to help Child Support Services get support from the other parent, unless you have a good reason, such as a risk of violence. Illinois passes all the support collected on to you, and it doesn’t lower your TANF. Food stamps (SNAP) don’t require this.

• Cash assistance (TANF): helping Child Support Services means, for example, naming the other parent and going to paternity tests and court dates. HFS explains your rights.
• All support goes to you: since July 2024, IDHS passes all collected support to families on TANF and doesn’t count it for TANF. The first $100 (one child) or $200 (two or more) comes as its own monthly payment, and the rest follows separately.
• Food stamps (SNAP): USDA’s state options report lists Illinois as a state that doesn’t make food stamps depend on helping with child support. Support you receive still counts as income for SNAP.

TANF, SSI, and SNAP don’t count as income for child support, under 750 ILCS 5/505(a)(3)(A). The Illinois child support guide covers how this works.

In 2026, a paying parent with gross income of $997.50 a month or less usually owes $40 a month per child, up to $120. A parent with no income, or who can’t work because of a disability or time in jail, prison, or an institution, usually owes $0.

• Minimum order: $997.50 is 75% of the 2026 federal poverty level for one person. The $120 limit covers all of the parent’s children, split equally, so a parent with children in other families pays less per child.
• $0 order: it also applies to a parent whose only income is need-based benefits, such as SSI or TANF.
• Shared care: the minimum order applies only without shared care; with 146 or more overnights each, the shared care formula sets the amount.
• Earning less by choice: a judge can count income a parent could earn if they choose not to work or work less than they could.

See 750 ILCS 5/505(a)(3.2a) to (3.3b).

No. When the parents’ net incomes add up to more than $27,375 a month, a judge decides support for that family. It can’t be less than the schedule’s top amount ($3,547 for one child).

The calculator above uses the top amount at higher incomes, split by income share. See 750 ILCS 5/505(a)(3.5).

Yes, when the standard amount from the schedule would be unfair or wouldn’t fit the family. The judge must write down what the standard amount would be and why the order is different.

A judge looks at the children’s and parents’ money and needs, the way the children would have lived if the parents had stayed together, and the children’s physical, emotional, and educational needs. Reasons the law lists include unusually high medical costs and a child’s special needs. See 750 ILCS 5/505(a)(2) and (3.4).

Ask Child Support Services at the Department of Healthcare and Family Services (HFS) to review your order, or file a motion in circuit court. You usually need to show a big change in your situation since the order was made. Keep following the current order until it changes.

• Through HFS: if your case is with Child Support Services, either parent can ask for a free review online or at 888-245-1938. HFS reviews orders every three years, and the new amount usually must differ from the old one by at least 20%.
• Through the court: file a motion to modify with the circuit clerk, using the statewide approved child support forms.
• Jail or prison, from January 2027: a parent held more than 180 days is treated as unable to pay. The order drops to $0 when a notice that the parent is in jail or prison is filed and no one objects within 45 days, under Public Act 104-0733.

The rules are in 750 ILCS 5/510. The Illinois child support guide walks through each step.

Yes. HFS publishes the Illinois Child Support Estimator, which also adds child care, health insurance, and other adjustments.

The Illinois Child Support Estimator can use the standard tax table or each parent’s actual taxes. HFS posts the current tables on its Income Shares page; they were last updated March 20, 2026.