Illinois uses the Income Shares model. Parenting time credit kicks in at 25% (91 nights/year).
Every overnight above 91 nights/year reduces your payment. Here's how Illinois's threshold compares:
Formula Model: Income Shares
How It Works: Income shares model since 2017. Both parents' net income considered.
Parenting Time Threshold: 25% of overnights (91 nights/year)
PT Credit Method: Shared Parenting Cross-Credit (146+ nights). At 146+ overnights (40%), full cross-credit. Below: sliding credit from 25%.
Illinois switched from a percentage model to Income Shares in 2017 — some older orders may still use the old formula.
Based on $6,000/mo income, 2 children, 20% parenting time
In Illinois, your parenting time credit activates at 25% of overnights (91 nights/year). Every night above this threshold reduces your payment.
Illinois's Income Shares model considers both parents' incomes. If your ex earns more than reported, gathering evidence of unreported income can significantly reduce your share.
Health insurance and childcare costs are typically split proportional to income in Illinois. If you're carrying the insurance, make sure you're getting credit.
Most Illinois courts allow a modification review every 3 years OR when there's a 20%+ income change — whichever comes first.
Keep a log of every dollar you spend on your kids beyond the order — extracurricular activities, school supplies, clothing. Courts factor documented expenses into deviation requests.
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Illinois uses the Income Shares model, which combines both parents' gross monthly incomes to determine a basic support obligation from a schedule table. Your share is proportional to your percentage of combined income. Income shares model since 2017. Both parents' net income considered.
In Illinois, once your parenting time exceeds 25% of overnights (approximately 91 nights per year), you receive a credit that reduces your obligation. A 50/50 custody arrangement typically results in the largest reduction.
Yes — under the Income Shares model, both parents' incomes are combined to determine the total support obligation. If your ex earns more, your proportional share decreases. This is one of the strongest levers for reducing your payment.
You can request a modification if there's been a substantial change in circumstances — like a 20%+ income change, job loss, new custody arrangement, or the child aging out. Illinois courts review modifications based on updated financial worksheets. Most allow a review every 3 years even without a change.
Most Illinois modifications are processed in 30–90 days after filing. Some counties offer administrative review (faster, no court date), while others require a hearing. Keep paying your current amount while the review is pending — stopping creates arrears that hurt your case.
Never stop paying — even if you can't afford the full amount. File a modification request immediately. Illinois courts can adjust your obligation retroactive to the filing date (not before). Document your financial hardship: pay stubs, termination letters, medical bills. Some counties offer payment plans for arrears.
Moving or comparing? See how neighboring states calculate child support.
2,000+ Fathers have used our step-by-step guide to file a modification — most without hiring a lawyer. The exact scripts, templates, and 30-day action plan that save Dads an average of $312/month.
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This is an educational estimate — not legal advice or a court order. Only a court or agency can set official child support. Actual obligations depend on factors not captured here. ChildCustodyPros.com is not a law firm. For guidance specific to your case, consult a licensed family law attorney in your state.
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