Illinois’ NEW (7/1/2017)
Child Support Law

by Wes Cowell; updated 2 September 2017 -- suggest a correction.

Illinois has finally adopted the "income shares" model for determining child support . . . joining 43 other States in the modern age.   Child support obligations are apportioned between parents by comparing their respective incomes and, in some cases, the amount of time the children spend with each parent.  Need advice?  Call, leave your info, or schedule a consultation.

BOTH parents have a duty to support their children.  It used to be that in most cases the kids would spend most of their time with Mom and not so much time with Dad.  Moreover, most Dads earned a LOT more than most Moms.  Times have changed.  Today, 50/50 parenting schedules are common, women make up nearly 50% of the workforce, and, although men generally earn more than women, the gender pay gap is closing.



The Income Shares Model at-a-Glance

Application -- When Can I Start Using It?

You're Probably Stuck with It

Determining Net Income

Gross Income Defined

"Standardized" (Simplified) Taxes 

"Individualized" Taxes

Avoiding the Tax Tables


Temporary Relief

Evidentiary Hearing

Small Business Income

Accelerated Depreciation

Perks and Reimbursement

Adjustments to Income

Supporting Other Children

Maintenance Payments

Asymmetrical Parenting

Simple Example

Shared Parenting: 146 Overnights

Shared Parenting Time Example

Split Parenting

School and Extra-Curricular Expenses

Child Care Expenses

Health Care and Medical Costs

Unemployment and Underemployment

Minimum Orders

Deviations from Income Shares Results

High Income Parents

No-Shows and Non-Cooperation

Income Shares At-a-Glance:  Under Illinois' new (7/1/17) child support law, Mom's and Dad's net incomes are combined to determine the "Basic Child Support Obligation."  That is the amount of financial support the child(ren) should receive from their parents -- BOTH parents.  The Basic Child Support Obligation is then apportioned between Mom and Dad based on their respective net incomes.


If the child spends at least 40% of overnights with each parent, the Basis Child Support Obligation is increased by 50% and the result is apportioned between Mom and Dad based on their respective incomes and the amount of time the child spends with each parent. 

Application -- Substantial Change In Circumstances ONLY:  You can't use the new law as the SOLE basis for seeking a change in your child support obligation.  You can't just go into court and say "Hey, I heard the law changed and so now I want a do-over!"  You MUST have some substantial change in circumstances (a change in employment, income, the parenting schedule, a relocation, etc.) to invoke the new law.  750 ILCS 5/510(a).

You're Mostly Stuck With It:  The law says that the court MUST use the income shares formula unless it finds that doing so would be inappropriate.  To determine whether the income shares results would be appropriate, the court must consider

  1. the financial resources and needs of the child;

  2. the financial resources and needs of the "custodial" parent;

  3. the standard of living the child would have enjoyed had the marriage or civil union not been dissolved;

  4. the physical and emotional condition of the child and his or her educational needs; and

  5. the financial resources and needs of the "non-custodial" parent.

750 ILCS 5/505(a)(2).​


Some kids are more expensive than others.  Some parents face financial circumstances that set them apart.  If you ask to get away from the income shares formula, the court will consider the above factors and decide whether to set child support in an amount different from the determination under the income shares formula.  It's rare, but it happens.

Determining Net Income:  Child support is determined in each case by looking at Mom's and Dad's net incomes.  Under the old (pre-7/1/17) law there were a lot of court squabbles over how to determine "net income."  Parents would argue about whether taxes were calculated properly, whether some payments were income or reimbursements, whether overtime, commissions, or bonuses were accurate or likely to continue . . . and on and on.


The new law eliminates most of those squabbles by making most people determine their net income using "standardized  taxes" as defined by Illinois' Department of Healthcare and Family Services (HFS) "Gross Income Conversion Table" (750 ILCS 5/505(a)(3)(C)(II)).  The table sometimes produces small variances from hard number-crunching, so compare results from the table with your own math and go with the option that suits you best:

Gross Income:  Gross income means "all income from all sources," (750 ILCS 5/505(a)(3)(A)) before "adjustments," and including spousal maintenance payments, but NOT INCLUDING:

  1. means-tested benefits like TANF, SSI, and SNAP and

  2. benefits and income (child support, survivor benefits, and foster care payments) received by the parent for other children in the household. 

SSDI and Social Security Retirement benefits paid for the benefit of the child must be included in the disabled or retired parent's gross income for purposes of calculating the parent's child support obligation, but the parent is entitled to a child support credit  for the amount of such benefits paid to the other parent for the child.

Spousal maintenance received pursuant to a court order (in the pending proceedings or any other proceedings) must be included in the recipient's gross income for purposes of calculating that  parent's child support obligation.


HFS "Standardized" Tax Table:  Most folks see all their income in the form of a paycheck from one or two jobs.  To determine "net income," just grab the most recent pay-stubs or last years's W-2s and go to the HFS's Gross Income Conversion Table.   That's all there is to it:  find the gross income on a paycheck, last year's W-2, or last year's tax return, and plug it into the HFS table.  The table tells you the net income.

The standardized tax amount represents what the income earner would pay in federal and state income taxes using a "single" tax filing status claiming the standard deduction and dependency exemptions for the minor child(ren) and Social Security and Medicaid taxes calculated at the FICA rate.  If you're a teacher, a cop, a railroad worker, etc. and you don't pay into Social Security, no worries -- the formula applies those taxes to your gross income so your support obligation will be calculated just like everyone else's.

"Individualized" Taxes:  Some folks may want to skip the State's "standardized," black-box tax tables and instead do it the old-fashioned way with paper-and-pencil:  subtract from gross income the aggregate of properly calculated federal and state income tax, Social Security or mandatory retirement contributions, and Medicare tax.  That's it -- forget about union dues, student loan repayments, or money spent to produce income -- subtract the basic taxes and the result is "net income" . . . so sayeth the law. 

 The judge will conduct a hearing and rule on the parties "net income."

Avoiding the Standardized Tax Table and Getting to the Judge:  There are three ways to avoid the HFS net income table:

1.  By Agreement.  Whether you and yours agree on anything else, if you agree on a "computation method" for the individualized tax amount that is different from the method  spelled out in the law, the judge MUST use your agreed-to method unless she rejects it for "good cause."

2.  "Summary" | Temporary | 501 Hearings:  Summary hearings are usually done at the outset of a case -- the parents have just split up and there are no orders in place about who pays which bills and how we keep food on the table and the lights turned on.  These are also known as "hearings for temporary relief" or "501 hearings" (section 501 of the law addresses "temporary relief").

In such hearings, either party may elect to have the judge -- not the HFS tables -- determine "net income" using the "individualized tax" method (subtract federal and state income taxes, Social Security taxes, and Medicare taxes, as above) on the basis of information contained in one or both parties' financial affidavit and supporting documents.  To opt in, you have to have your financial affidavit completed, your supporting documents in order, and have it all tendered to the other side. 

3.  Evidentiary Hearing:  In some situations you can get away from the State's "standardized" black box table, skip the law's narrow definition of "net income" (as in summary hearings) and instead present all the nitty-gritty to the judge. The law says that "[i]In each such case (unless there is an agreement as per 1., above), the individualized tax amount shall be as determined by the court on the basis of the record established."  That last line " . . . one the record established" opens the door to get all sorts of information before the judge that isn't easily presented on the financial affidavits. 

Small Business Income  If you're self-employed (sole proprietorships, closely-held corporations, partnerships and other self-employment), the law looks to your "net business income;" defined as "gross receipts minus ordinary and necessary expenses required to carry on the trade or business."  There's not a lot of wiggle room here.  The court must, by law, apply the accelerated component of your depreciation expense.  The judge determines whether any given expense is excessive or inappropriate.  If you try to sandbag income as "retained earnings," its a win-some-lose-some proposition.  See my article:  Small Business Income and S-Corps..

Perks and Reimbursements:  These get counted as income.  This is nothing new -- it's all part of the "all-income-from-all-sources" mantra that the court has employed for ages.  If your employer or business provides you with a car, a phone, housing, a laptop, travel miles, free internet connections, or even an allowance for meals, it's all counted as income if it's "significant in amount and reduces personal expenses."


Adjustments for Other Children and Maintenance:  A party's gross income may be reduced if he or she is supporting children from another relationship (with or without a support order), and if he or she is paying maintenance in the pending proceeding.

Other Children:  If a parent is legally responsible for the support of children not subject to the pending proceeding, he or she may deduct from gross income:

  1. the amount of support actually paid pursuant to a support order; or

  2. the lesser of:

    1. the amount of financial support actually paid by the parent for children living in or outside of that parent's household or

    2. 75% of the support the parent would pay under the child support guidelines.

Example:  Dad has three kids from marriage 1, is ordered to pay $1,000.  Dad, however, pays only $800 / month based on an out-of-court agreement with Former Wife 1.  Dad may deduct $800 from his monthly gross income when calculating support for the children in marriage 2.

Example:  Dad has two kids from a prior relationship but no support order.  Crunching the numbers, he shows he would be ordered to pay $1,000 / month for support.  75% of that is $750.  He proves he actually pays $550 / month to support the children.  Dad my deduct $550 from his monthly gross income when calculating support for the children in the pending proceeding.  

Example:  Dad has three kids from marriage 1, they live with him and Former Wife 1 pays $1,000  / month to Dad pursuant to a child support order.  The kids from marriage 2 will go back-and-forth between mom and dad on a 50/50 parenting schedule.  Dad shows that under the guidelines, he'd have to pay $1,000 for the children of marriage 1.  75% of that is $750.  Dad proves that he actually spends $745 / month supporting the children of marriage 1.  He may deduct $745 from his gross income when calculating support for the children in marriage 2.


Example: Dad has 2 kids from marriage 1, is ordered to pay $1,000 but pays nothing.  75% of his support obligation is $750, but he gets no deduction because he's not "actually paying."

Maintenance Payments:  Maintenance obligations actually paid or payable pursuant to a court order in the pending proceeding may be deducted from the payor's gross income and added to the recipient's gross income when determining net income for child support purposes.          

Asymmetrical Parenting Schedule:  If your kids spend most of their time with one parent, child support is determined by:

  1. Find each parent's net income using the standardized or individualized tax methods and applying any adjustments (above);

  2. Go to the HFS table and use the parents' combined net income to find the Basic Child Support Obligation.

  3. Apportion the Basic Support Obligation between the parents based on their respective net incomes.

  4. The parent owing support pays to the other his or her share of the Basic Support Obligation. 

  5. Add to that amount the payor's proportional share of any

    1. health insurance premiums,​

    2. qualifying day care costs,

    3. school and extra-curricular expenses.

That's  it.  You're done.

Simple Example:  Mom nets $1,704 (on a gross of $2,000) and Dad nets $2,382 (on a gross $3,000); they have one child who spends most of the time with Mom.  Their combined net income is $4,087.  Mom's share of that net income is 41.69% and Dad accounts for 58.31%.  The Basic Child Support Obligation for $4,087 is $844 / month (this figure comes from a table able maintained by the Illinois Department of Healthcare and Family Services).  Dad would pay to Mom 58.31% of the Basic Child Support Obligation of  $844, or $492 / month (this is actually a little bit MORE than what Dad would have paid under the old, "percentage guidelines" way of calculating support).

In the above example, Dad would also pay to Mom 58.31% of the child's health insurance costs, child care expenses, and school and extra-curricular activity expenses.

"Shared Parenting" Schedule:  In cases where the child(ren) spend(s) at least 146 overnights / year with each parent -- the law's definition of "shared parenting" -- a further reduction kicks in.  750 ILCS 5/505 (a) (3.8).  146 overnights is a robust parenting schedule.  That's  40% of 365 nights.  It works out to 6 overnights every two weeks.  Let's take a look at the calendar:

  • "Alternating weekends" from Friday evening to Sunday evening will get you to 52 overnights / year.

  • Add two one-week vacations and you're up to 66 overnights.

  • Add half of the winter school break (8 overnights) = 74 overnights.

  • Add half of Spring Break (about 3 overnights) = 77 overnights

  • Add, say, 5 more overnights for long weekends attached to holidays or school closing days and you're up to 82 overnights . . . leaving 64 to go -- you're going to have to add another three overnights every two weeks to make it.

Lots of parents live too far away to accommodate such a robust schedule.  Some parents have to travel for work or have work schedules that won't accommodate 146 overnights.  And parents aren't the only players in this game.  Most kids have commitments and social schedules that restrict where they can easily spend the night.  If you're in the 146+ group, however, calculating support is easy as pie -- here's what you do:

  1. Find the each parent's net income using the standardized or individualized tax methods and applying any adjustments (above);

  2. Determine each parent's separate support obligation using the HFS table.

  3. Add the separate obligations of the parents and multiply the sum by 1.5 to get teh "Shared Physical Care Support Obligation" (that's right:  (Mom's support + Dad's support) x 1.5 = Shared Support)

  4. Apportion the Shared Support Obligation between Mom and Dad according to their respective net incomes.

  5. Multiply each parent's apportioned share by the percentage of overnights the child spends with the other parent.

  6. Offset the two amounts.

  7. That's it -- the parent owing more pays the difference between the two amounts.

Shared Parenting Time Example:  Using the above example, Mom nets $1,704 (on a gross of $2,000) and Dad nets $2,382 (on a gross $3,000); they have one child who spends 60% of his time (219 overnights / year) with Mom and 40% (146 overnights) with Dad.  Their combined net income is $4,087.  Mom's share of that net income is 41.69% and Dad accounts for 58.31%.  The Basic Child Support Obligation for $4,087 is $844 / month.


Because the child spends at least 146 overnights with each parent, we multiply the Basic Support Obligation by 1.5 to get the "Shared Physical Care Support Obligation" ($844 x 1.5 = $1,266).  We allocate the Shared Support Obligation between Mom and Dad based on their respective net incomes:  Mom's share would be $528 ($1,266 x .4169) and Dad's share would be $738 ($1,266 x .5831).

Mom would owe Dad $528 x .4 = $211

Dad would owe Mom $738 x .6 = $443

Offsetting those figures, Dad owes Mom $232 / month ($443 - $211 = $232).

Split Parenting:  "Split Parenting" refers to cases where each parent cares for at least one child -- as kids get older, it sometimes happens that boys-go-with-dad-and-girls-go-with-Mom.  It's not uncommon.  If you've got a split parenting situation, use separate worksheets to determine the support each parent owes the other (each parent calculates as if the child(ren) in his or her care is/are the only child(ren) of the parties) , then offset the obligations with one parent owing the other the difference.

School and Extra-Curricular Expenses:    Expenses for school and extra-curricular activities are not considered to be part of child support.  The court, if asked, may tack on a duty to contribute to a child's extra-curricular expenses.   There are limitations and there's a right way to do it.  See my article:  Child Support Plus for more information.

Child Care Expenses:  The court may tack on child care expenses above-and-beyond child support.  Payments may be ordered to go either to the other parent (as reimbursement) or the child care provider, directly.  See my article:  Child Support Plus for details. 

Health Care and Health Insurance:  The court can order the parents to provide for a child's health insurance.  The prior law assigned this responsibility solely to the parent paying support.  Under the 2017 law, however, the court can allocate the burden any way it wants.  Most parents can figure this out on their own without a fight -- everyone wants their kids have good health care and good insurance coverage.  The court will look at each parent's insurance options and figure out the best coverage and cost.  If you need more information, see my article:  Child Support Plus.

Unemployment and Underemployment:  If a parent is voluntarily unemployed or voluntarily underemployed, child support is determined using that parent's "potential income."   The judge looks to that parent's work history, occupational qualifications, prevailing job opportunities, the ownership by a parent of a substantial non-income producing asset, and earnings levels in the community.  If there is insufficient work history to determine employment potential and probable earnings level, there is a rebuttable presumption that the parent's potential income is 75% of the most recent United States Department of Health and Human Services Federal Poverty Guidelines for a family of one person. 

Minimum Orders:  If a parent is earning less than 75% the federal poverty guideline amount (the guideline is about $12,000 / year, so 75 would be about $9,000 / year) support is set at $0 / child / month but that maxes out at $120 / month.  If that's the case, that $120 / month is divided equally amongst all of the obligor's children.


For parents with no income (recipients of  means-tested assistance like TANF and SSI) or who cannot work due to a medically proven disability, incarceration, or institutionalization, there is a rebuttable presumption that the $40 per month minimum support order is inappropriate and a zero dollar order shall be entered. 

Deviation:  The court may consider deviating from the result produced by either method.  Remember, the "guidelines" are just that -- GUIDELINES -- and the court may deviate from them.  In the granddaddy of all "deviation" cases (note:  this was decided in 1986, long before the current law, but the argument still works) William Blaisdell argued his position that under Section 505(a), courts are mandated to follow literally the schedule for child support.  The Illinois Appellate Court handed him a quick loss, saying:


"If this reading is correct, the function of the court is reduced to that of a computer or robot. In this case, the sole function of the court would be to determine the net income of the noncustodial parent, determine the number of children, and calculate the amount of child support by applying the percentage of net income stated in the schedule. However, respondent has failed to show that the statute can or should be read to effectively prohibit judicial discretion."

Boris v. Blaisdell, 142 Ill.App.3d 1034, 97 Ill.Dec. 186, 492 N.E.2d 622,  (Ill. App. 1 Dist., 1986)

As an aside, Blaisdell is an excellent "lawyer's case" because it lays out the legislative history of Illinois' child support laws and includes bits of legislative testimony and explains the pre-legislative de facto guidelines used by local circuit courts.


Any deviation must serve the "best interest of the child," must fall within one of the law's proscribed "deviation factors" (but there's always the "any other factor" catch-all) and must be spelled out in detail in the resulting child support order.  The "deviation factors" include:


(A) extraordinary medical expenditures necessary to preserve the life or health of a party or a child of either or both of the parties;

(B) additional expenses incurred for a child subject to the child support order who has special medical, physical, or developmental needs; and

(C) any other factor  the court determines should be applied upon a finding that the application of the child support guidelines would be inappropriate, after considering the best interest of the child.

750 ILCS 5/505(a)(3.4)

High Income Parents:  The Basic Child Support Obligations Table prepared by HFS goes up to a COMBINED adjusted net income of $30,024.99 /  month ( $360,300 / year).  Beyond that, the formulas stop and the law tells judges to use their discretion but the basic support obligation may not be less than the highest support level determined by the HFS tables.  This is the way it was done in decades past.  Most judges used to subscribe to a rule-of-thumb that if a family's net income cracked the $300 - $350,000 level, the judge would deviate from  the "percentage guidelines."  Nothing has changed for higher-income families.  See my article on "Deviation From Income Shares Results."

No-Shows and Non-Cooperation:  What do you do when one parent doesn't show up or the court lacks personal jurisdiction?  If you're trying to get support established for an earlier period, the law allows the court to presume that the supporting party's net income for the prior period was the same as his or her net income at the time the order for current support is entered.  If a parent's net income cannot be determined, the court orders support in an amount it considers reasonable in the particular case.

If the non-custodial parent doesn't cooperate and doesn't show up, you can still go forward using evidence obtained by subpoena.  The rules of evidence are relaxed when a parent refuses to cooperate.  You'll still have to follow the right procedure, but the whole process is affordable.

“My son had special neds and I needed more than the 20% my ex said I was entitled to.  Wes helped me get everything I needed.  
–Mary M.., Schaumburg, Cook County, IL
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