An educational estimate based on the Illinois income shares schedule
Illinois uses an income shares model in 750 ILCS 5/505. The court determines each parent's monthly net income, adds those amounts together, and selects the corresponding amount from the schedule of basic child support obligations based on combined monthly net income and the number of children. Each parent is responsible for a share of that basic obligation equal to that parent's percentage of combined net income, under 750 ILCS 5/505(a)(1.5).
This page uses the Illinois Department of Healthcare and Family Services Income Shares Schedule Based on Net Income that became effective March 20, 2026, published at https://hfs.illinois.gov/content/dam/soi/en/web/hfs/childsupport/parents/2026ilschedofbobligations.pdf. The HFS Income Shares page states that Illinois updates that schedule annually and that the most recent revision is effective March 20, 2026. The schedule has 547 combined-net-income bands from $25.00 through $27,374.99, with columns for one through six children.
The numbers below show how the pieces fit together. They are an educational example, not a prediction for your case.
750 ILCS 5/505 says a court may use its discretion if combined adjusted net income exceeds the highest level of the schedule, except that the basic child support obligation shall not be less than the highest level set forth in the schedule. The highest published band is $27,325.00 through $27,374.99, where the one-child through six-child amounts are $3,547, $5,210, $6,069, $6,779, $7,457, and $8,106. This page uses those highest published amounts and does not invent a percentage of income above the schedule.
The published schedule begins at a combined monthly net income of $25.00. If combined monthly net income is below $25.00, this page does not invent a schedule amount. Separately, 750 ILCS 5/505(a)(3.3a), in the text in effect until January 1, 2027, creates a rebuttable presumption of a $40 per month per child minimum, with a $120 monthly cap, for an obligor whose actual or imputed gross income is at or below 75 percent of the HHS poverty guideline for one person. The 2026 guideline for one person is $15,960 a year. That presumption is based on gross income, and this page asks for net income, so it does not replace a schedule result with the $40 figure. 750 ILCS 5/505(a)(3.3b) addresses a zero-dollar order in listed situations such as means-tested assistance. This page does not invent that finding.
Under the text of 750 ILCS 5/505(a)(3.8) in effect until January 1, 2027, shared physical care applies if each parent has 146 or more overnights a year. The basic obligation is multiplied by 1.5. Each parent's share of that shared-care obligation is based on that parent's percentage of combined net income. Each parent's resulting obligation is then multiplied by the percentage of time the child spends with the other parent, and the two results are offset. Public Act 104-733 amends that paragraph effective January 1, 2027, including a 110-overnight definition and an adjustment table. This page uses the 146-overnight text that is in effect on November 6, 2026.
Reasonable child care expenses and the child's health insurance premium are allocated by each parent's share of combined net income. This page treats the childcare, health insurance, and unreimbursed medical amounts you enter as costs paid by the parent who receives support, and it adds the paying parent's income share of those amounts. It does not subtract the federal child care tax credit.
The court may deviate from the guideline amount under 750 ILCS 5/505(a)(3.4). This estimate does not apply those discretionary deviations.
The court combines both parents' monthly net income, looks up the basic child support obligation on the HFS schedule, and assigns each parent a share equal to that parent's portion of combined net income. Childcare and health insurance costs are generally allocated the same way. If each parent has at least 146 overnights, the court also applies the shared physical care calculation in 750 ILCS 5/505(a)(3.8).
The statute starts with net income as defined in 750 ILCS 5/505. HFS also publishes a standardized gross-to-net conversion table. This page does not apply that table or guess tax withholding. Enter monthly net income if you have it. If you enter gross pay, the result will usually be higher than a court worksheet.
The 2026 schedule ends at $27,374.99 of combined monthly net income. The statute then lets the court use discretion, but the basic obligation cannot be less than the highest published schedule amount. This page uses that highest published amount and does not invent an above-schedule percentage.
If combined monthly net income is below the first published band of $25.00, this page does not invent a schedule amount. The $40 minimum in 750 ILCS 5/505(a)(3.3a) depends on the paying parent's gross income compared with 75 percent of the federal poverty guideline, which this page does not convert from the net figure you enter.
Yes, when each parent has at least 146 overnights a year under the statute text in effect until January 1, 2027. The required method is the 1.5 multiplier and offset in 750 ILCS 5/505(a)(3.8), not an invented overnight discount.
Start with 750 ILCS 5/505 on the Illinois General Assembly site, the HFS Income Shares page, and the 2026 Income Shares Schedule PDF linked from that page. Online calculators are for information only, and a court may consider factors that are not part of an estimate.
Estimate only. This page is an educational tool, not legal advice, and it is not a substitute for the official guidelines schedule, a court worksheet, or advice from a qualified attorney. Nothing you enter is stored or sent to us from this page itself. Compare every figure with the current statute and schedule before you rely on it.