Question 1

# Illinois Child Support — Frequently Asked Questions

Accepted Answer

> **Based on Illinois guidelines effective March 5, 2025 (750 ILCS 5/505). Laws change — verify with the current statute and the Illinois Department of Healthcare and Family Services (HFS) before relying on any information here.**

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Question 2

1. How is child support calculated in Illinois?

Accepted Answer

Illinois uses an **income shares model**. Both parents' incomes are considered — not just the paying parent's. Here's the basic process:

1. Each parent's monthly gross income is converted to **net income** using a standardized government tax table (not your actual tax return).
2. Both net incomes are combined and used to look up the **Basic Support Obligation (BSO)** from the Illinois Schedule of Basic Obligations — a published chart that varies by income level and number of children.
3. Each parent pays their **proportional share** of the BSO based on their percentage of the combined income.
4. **Add-ons** like health insurance premiums and work-related childcare are split the same way and added to the base amount.

The result is the monthly support obligation for each parent. In most cases, the parent with fewer overnights pays their share to the other parent.

*This calculator provides an estimate based on these guidelines. Consult a family law attorney for advice specific to your situation.*

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Question 3

2. What counts as income in Illinois?

Accepted Answer

Illinois has a broad definition of income. It includes wages, salary, tips, bonuses, commissions, self-employment income, Social Security benefits, Veterans Administration benefits, pension and retirement distributions, interest, dividends, rental income, and even gambling winnings.

What typically does **not** count:
- Means-tested public assistance (TANF, SNAP, SSI, Medicaid)
- Social Security or VA benefits paid **from the obligor's account directly to the children** — these are applied as a dollar-for-dollar credit against the obligation instead of being added to income

If a parent is voluntarily unemployed or working less than they could, the court may assign ("impute") income based on their earning capacity rather than actual income.

*Income determinations can be contested. Consult a family law attorney for advice specific to your situation.*

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Question 4

3. How does parenting time affect the support amount?

Accepted Answer

For most families, the amount of parenting time does not directly change the calculated support amount — it only determines which parent pays the other.

However, if **both parents have at least 146 overnights per year** (about 40% of the year each), Illinois applies a **shared physical care formula**. The Basic Support Obligation is multiplied by 1.5 to account for the higher costs of maintaining two full households, and then each parent's obligations are offset against each other. The parent who comes out owing more pays the net difference.

**Split custody** (where each parent is the primary home for at least one child) requires two separate calculations — one for each group of children — which are then netted together. This is a complex scenario best handled with an attorney.

*Parenting time calculations can significantly affect your result. Consult a family law attorney for advice specific to your situation.*

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Question 5

4. Is there a minimum or maximum support amount?

Accepted Answer

**Minimum:** If the obligor's gross income is at or below $978 per month (approximately 75% of the federal poverty guideline), a minimum order applies: $40 per child per month, capped at $120 per month total. If your calculated amount is higher than this minimum, the higher amount applies.

A **zero-dollar order** may be issued if the obligor has no income, receives only means-tested public assistance, is medically unable to work, or is incarcerated. Illinois law specifically states that incarceration is not considered voluntary unemployment.

**Maximum:** The schedule goes up to $26,724.99 in combined monthly net income. When both parents' combined income exceeds this level, the court has **discretion** to set support above the schedule — there is no statutory cap on what a high-income parent can be ordered to pay.

*Minimum and maximum provisions involve specific legal requirements. Consult a family law attorney for advice specific to your situation.*

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Question 6

5. What are add-ons and how are they split?

Accepted Answer

Add-ons are additional expenses beyond the basic support obligation. Illinois recognizes two main add-ons that are split by each parent's income share:

**Health Insurance:** The child-only portion of the premium is split proportionally by income. The court will also consider whether the premium is "reasonable" — generally no more than 5% of the providing parent's gross income. If it exceeds that, a cash medical support order may be substituted.

**Work-Related Childcare:** Daycare, after-school care, or summer programs while parents work are prorated by income share. The childcare must be work-related — general babysitting typically doesn't qualify.

**Extraordinary Medical Expenses:** Uninsured, out-of-pocket medical costs can also be divided, but the court allocates these at its discretion rather than using a fixed formula.

*How add-ons are calculated and allocated can vary case by case. Consult a family law attorney for advice specific to your situation.*

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Question 7

6. Can child support be modified?

Accepted Answer

Yes, but it requires going back to court. Illinois law requires proof of a **substantial change in circumstances** before a court will modify an existing order. This could include a significant income change for either parent, a change in the child's needs, a change in parenting time, or other major life changes.

There is no automatic modification — you must file a petition, and the court must approve any change. Informal agreements between parents are not legally binding and do not change the court order.

*Modification eligibility depends on your specific circumstances. Consult a family law attorney for advice specific to your situation.*

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Question 8

7. When does child support end in Illinois?

Accepted Answer

Child support generally ends when the child turns **18** or graduates from high school, whichever is **later** — but no later than age **19**. If the child is still in high school at age 18, support continues until graduation or the end of the school year in which they turn 19.

Support may be **extended** for a child with a disability or special needs who is unable to support themselves.

Illinois also has a **separate process** for college contribution (post-secondary education support under §513), which is distinct from regular child support and requires a separate court action.

*Support termination dates depend on your child's situation. Consult a family law attorney for advice specific to your situation.*

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Question 9

8. What happens if a parent's income is very low?

Accepted Answer

Illinois has specific protections for low-income parents:

- If your gross income is at or below $978 per month (75% of the federal poverty level), the **minimum order provisions** apply: $40 per child per month, up to $120 per month total. This minimum can be rebutted in limited circumstances.
- If you receive only means-tested public assistance (TANF, SNAP, SSI, Medicaid) or are medically unable to work, a **zero-dollar order** may be entered.
- Incarceration is not treated as voluntary unemployment — an incarcerated parent may also qualify for a zero or reduced order.

Courts can also consider whether a low-income parent should receive a deviation from the guidelines due to financial hardship.

*Low-income provisions have specific eligibility requirements. Consult a family law attorney for advice specific to your situation.*

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Question 10

9. What if one parent is self-employed?

Accepted Answer

Self-employment income is included in Illinois child support calculations, but courts look at it carefully. Self-employment gross income is reduced by legitimate business expenses — but not all expenses claimed on a tax return are automatically accepted. Courts may add back expenses that primarily benefit the parent personally (e.g., a car used mostly for personal purposes).

Self-employed parents also receive a deduction for the employer-side of FICA taxes (the portion an employer would otherwise pay), which reduces their effective tax burden in the calculation.

Because self-employment income can be difficult to verify and is subject to more scrutiny, self-employed parents often benefit from legal representation.

*Self-employment income determinations are often contested. Consult a family law attorney for advice specific to your situation.*

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Question 11

10. Does spousal maintenance (alimony) affect child support?

Accepted Answer

Yes. Spousal maintenance paid or received under a court order affects the income used to calculate child support:

- **Pre-2019 orders** (entered before January 1, 2019): Maintenance paid is deducted from the payer's gross income before tax conversion; maintenance received is added to the recipient's gross income. This reflects the old federal tax treatment.
- **Post-2018 orders** (entered on or after January 1, 2019): Maintenance is adjusted at the net income level instead, reflecting the TCJA's elimination of the maintenance deduction.

If maintenance and child support are both being set in the same proceeding, the calculation becomes more complex.

*The interaction between maintenance and child support requires careful analysis. Consult a family law attorney for advice specific to your situation.*

Illinois Child Support Calculator

How Illinois calculates child support

Key inputs

What courts can adjust

Frequently Asked Questions