Illinois Child Support Calculator 2026 – 750 ILCS 5/505 Guidelines
Use our free Illinois child support calculator for 2026 to estimate guideline support under 750 ILCS 5/505. Illinois uses Income Shares model. Therefore, the court combines both parents’ monthly net incomes and consults HFS Schedule of Basic Child Support Obligations. For example, the schedule matches combined income up to about $30,025 to basic obligation. In addition, if combined exceeds highest level, court has discretion per 505(a)(3.5). As a result, our calculator uses current 2026 schedule and shared care formulas for accurate estimate.
Combined net income schedule • 146+ overnights x1.5 shared care • HFS conversion table
How Illinois Child Support Is Calculated in 2026:
Illinois calculation has four steps. First, determine net income. Second, lookup basic obligation. Third, split proportionally. Finally, apply shared care adjustment if 146+ overnights. Because of this process, support reflects income shares and parenting time. In addition, courts add healthcare and childcare.
Step 1 – Determine Monthly Net Income
Illinois uses net income, not gross. Net income is computed using HFS standardized tax amount or individualized tax amount under 505(a)(3)(D). Standardized table updated annually, most recently March 5, 2025, assumes single filing status and standard deduction. Gross income includes wages, salaries, commissions, bonuses, self-employment net income, rental income, business distributions, pensions, Social Security, disability, unemployment, and other recurring sources. However, means-tested public assistance like SSI is excluded. For
self-employment, personal-benefit business deductions are added back. Therefore, court looks at pay stubs, two years tax returns, bank statements, bonus history, commission statements. In addition, maintenance is calculated first and then incorporated: maintenance increases recipient’s net income and decreases payor’s net income for child support purposes. As a result, sequence matters.
Compare 146+ shared care with North Carolina 123+ nights joint custody and Ohio 90+ nights reduction. See also Pennsylvania 40% custody rule and Michigan parental time offset.
Step 2 – Lookup Basic Obligation Schedule:
Court adds monthly net incomes to get combined monthly net income and uses combined and number of children to find basic child support obligation on HFS Schedule. For example, at $5,000 combined, one child about $1,000, two children about $1,710. At $10,000 combined, one child $1,550, two $2,530. At $30,000 combined, one child $2,360, two $3,760. As income rises, basic obligation increases but at decreasing rate per economic data. Therefore, each parent’s percentage share equals their share of combined income multiplied by basic obligation.
Step 3 – Handle High Income Over $30,025
When combined adjusted net income exceeds highest level on Schedule, currently around $30,025 monthly net combined, court has discretion per 750 ILCS 5/505(a)(3.5). Minimum is highest level on schedule; maximum is whatever court finds appropriate based on child’s needs and parents’ resources. Therefore, high-income cases require expense statements and deviation analysis. For example, for $40,000 combined for one child, minimum is $2,360 plus additional amount court finds appropriate. As a result, high-income support is not fixed percentage.
Step 4 – Apply Shared Physical Care Adjustment 146+ Overnights
If each parent has child for 146 or more overnights per year, roughly 40% of time, basic obligation is multiplied by 1.5 under 750 ILCS 5/505(a)(3.8). Shared care obligation is then cross-credited based on each parent’s percentage of combined income and parenting time, with parent owing more paying difference. Therefore, 146-overnight threshold is hard line. Cases just under threshold use standard calculation; cases at or over apply 1.5 multiplier and cross-credit. For example, equal 50/50 time with unequal incomes still produces payment when incomes differ. In addition, SB 3524 passed 2026 creates new adjustment table for parents who have at least 110 overnights but fewer than 146 effective 2027. It also changes minimum-support threshold for low-income obligors from 75% to 100% of
Federal Poverty Guidelines while keeping $40 per month per child and $120 cap. As a result, 2027 will have tiered adjustment for 110-145 overnights.
Illinois Child Support Example:
Suppose Parent 1 net $4,500 and Parent 2 net $3,200. Combined $7,700. For 2 children, basic obligation about $2,200. Parent 1 share 58.4% = $1,284, Parent 2 share 41.6% = $916. Standard: Parent 1 pays $1,284 to Parent 2 if Parent 2 custodial plus childcare $500 x 58.4% = $292, total $1,576 per month.
However, if Parent 2 has 146 overnights (40% time), shared care applies: basic x1.5 = $3,300 total, shared $3,800? Actually $2,200 x1.5 = $3,300 shared, Parent 1 share $1,927 x 40% time? Wait cross-credit: Parent 1 adjusted $1,927 x 40% = $771? Let’s
calculate: $3,300 x 58.4% = $1,927 for Parent 1, x 41.6% = $1,373 for Parent 2, cross-credited by time: $1,927 x 146/365 = $771, $1,373 x 219/365 = $824, difference $53 Parent 2 pays? Actually $824-$771 = $53 Parent 2 pays Parent 1. As a result, shared care can flip payer when times close to equal and incomes similar. Therefore, parenting time disputes have child support implications.
Additional Expenses and Deviations:
Healthcare premiums, work-related childcare costs, and extraordinary expenses are added on top of basic obligation
and divided by same percentage shares. In addition, court can deviate under 505(a)(2) when guideline inappropriate
based on financial resources and needs of child, resources and needs of each parent, standard of living child would
have enjoyed, physical, emotional, educational needs. Deviations require specific findings. Therefore, guideline is
default, deviation exception.
Official Illinois Resources:
For official calculation, use Illinois Department of Healthcare and Family Services Division of Child Support Services
https://hfs.illinois.gov/childsupport or HFS administrative case no-cost path. Court cases require financial affidavit
sworn under penalty of perjury. SupportCalcUSA.com not affiliated with Illinois courts.
Explore other state calculators: Home | Texas guidelines | California formula | Florida method | New York rules | Pennsylvania model | Ohio schedule | Illinois income shares | North Carolina worksheets | Georgia Schedule C | Michigan offset equation | About Us | Contact Us
Frequently Asked Questions:
Income Shares under 750 ILCS 5/505(a)(1.5). Determine each parent monthly net income using HFS conversion table, add to get combined, lookup basic obligation on HFS Schedule by children, split proportionally by income share. Add healthcare, childcare, extraordinary expenses proportionally
Gross wages, salaries, commissions, bonuses, self-employment net, rental, business distributions, pensions, Social Security, disability, unemployment, recurring sources averaged. Net via HFS standardized tax amount or individualized tax per 505(a)(3)(D). Maintenance calculated first and incorporated.
146 or more overnights per year per parent, roughly 40% time, per 750 ILCS 5/505(a)(3.8). Basic x1.5 then cross-credited by income % and parenting time. SB 3524 effective 2027 adds new adjustment for 110-145 overnights.
No. Equal schedule still usually produces payment when incomes differ because shared care cross-credit still leaves difference based on income percentages. For example, higher earner still pays even at 50/50.
About $1,000 basic per schedule. Split proportionally: if Parent 1 $3k (60%) and Parent 2 $2k (40%), non-custodial pays 60% or 40% depending who is custodial, before add-ons.
Court discretion per 505(a)(3.5). Minimum is highest level on schedule ($2,360 for one child at $30k), maximum whatever court finds appropriate based on child needs and resources. Requires expense statements.
Yes, added on top of basic obligation and divided by same percentage shares per income. Healthcare premiums broken out from parent premium, childcare receipts required.
Yes, substantial change in circumstances per 750 ILCS 5/510. Job loss, raise, custody change, new needs qualify. Must file petition and show change.
At 18 and graduated high school, or 19 if still in high school, or emancipation: married, military, self-supporting, or court order. College expenses separate under 505(a)(3)(f).
Estimate only based on Income Shares schedule and 146+ shared care x1.5 formula. Actual order uses HFS Gross to Net Conversion Table updated March 5, 2025 and individualized taxes, low-income $40 per child $120 cap, future SB 3524 changes 2027. Not legal advice.