A child support order is based on financial and family circumstances at a particular point in time. Those circumstances do not always remain the same.
A parent may lose a job, receive a substantial raise, change careers, or experience a significant change in income. The amount of parenting time may change. Health insurance costs or other expenses for the child may increase. When circumstances materially change, the amount of child support established under an earlier order may no longer reflect the family’s current situation.
Illinois law allows child support orders to be modified under qualifying circumstances. A modification is not automatic, however, and parents should not simply begin paying or accepting a different amount because their financial circumstances have changed.
Keller Legal Services represents parents seeking and opposing child support modifications in Naperville, DuPage County, Kane County, Will County, and surrounding Illinois communities. We help parents evaluate whether circumstances support a modification, determine how current Illinois guidelines may affect the calculation, and address disputes over income and other financial information.
The primary statute governing modification is 750 ILCS 5/510, which provides that a child support order may generally be modified upon a showing of a substantial change in circumstances.
The law does not provide a single list of events that automatically qualify as a substantial change. Instead, the court evaluates the circumstances surrounding the existing order and what has changed since it was entered.
Situations that may lead a parent to request modification include:
The fact that something has changed does not necessarily mean child support will change. The court must determine whether the applicable legal requirements have been satisfied and, when modification is warranted, calculate the appropriate support obligation.
Parents who need information about how support is initially determined can review Keller Legal Services’ broader discussion of Illinois child support.
This is one of the most important questions in a child support modification case.
Illinois law allows modification based on a substantial change in circumstances, but whether a particular change is substantial depends on the facts.
A small fluctuation in income, for example, may not justify modifying an existing court order. A major and continuing change in a parent’s financial situation may present a much stronger basis for review.
The court may need to examine:
Section 510 also addresses future events that were contemplated when the existing order was entered. Unless a future event was expressly identified in the court order or incorporated agreement as contemplated and not constituting grounds for modification, foreseeability by itself does not prevent the event from being considered in determining whether circumstances substantially changed.
Yes. A parent receiving child support can seek an increase when circumstances support modification.
One common reason is a substantial increase in the other parent’s income. However, modification is not based simply on the idea that a parent who earns more should automatically pay more.
Illinois uses an income shares approach that considers the financial circumstances of both parents.
Under 750 ILCS 5/505, the basic calculation begins by determining each parent’s monthly net income, combining those incomes, identifying the appropriate basic support obligation, and allocating that obligation between the parents according to their respective shares of combined net income.
As a result, a meaningful change in either parent’s income may affect the calculation.
An increase may also become relevant when other circumstances affecting the support obligation have materially changed.
A parent paying support may also request a reduction when there has been a qualifying substantial change in circumstances.
Examples may include a significant involuntary reduction in income, job loss, or another material financial change.
The important distinction is that losing income does not automatically reduce the existing support order.
Until the order is modified through the appropriate process, the existing obligation generally remains in effect.
Courts can also examine the circumstances surrounding a reduction in income. A parent should not assume that voluntarily taking a lower-paying position, reducing work hours, or otherwise decreasing earnings will necessarily result in lower child support.
A modification case involving reduced earnings may therefore require more than showing current pay stubs. The circumstances that produced the change can matter.
Job loss is one of the most common reasons parents begin asking about child support modification.
The loss of employment may support a modification when it creates a substantial change in financial circumstances, but the analysis does not end with the fact that the parent is currently unemployed.
Questions may include:
Parents should act promptly when a significant income change occurs rather than allowing an unaffordable support obligation to accumulate while assuming the amount can simply be corrected later.
Timing is particularly important in Illinois child support modification cases.
Section 510 provides that support generally may be modified only as to installments accruing after due notice of the filing of the motion for modification.
Consider a parent who loses a job in January but waits until June to seek modification. The fact that the parent’s financial circumstances changed in January does not necessarily mean the court can simply rewrite all of the support obligations that accrued during the intervening months.
This is one reason waiting can be costly.
If your income has substantially changed and you believe your support order should be reviewed, addressing the issue promptly can protect you from relying on assumptions about what a court may later change.
When modification is appropriate, the court generally applies Illinois’ current child support framework.
Illinois’ guidelines are based on the parents’ combined net income and the number of children covered by the support order. Each parent’s percentage share of that combined income is then used in allocating the basic support obligation.
This means recalculating support can require current financial information from both parents.
Depending on the circumstances, relevant information may include:
A modification should therefore not be estimated simply by comparing one parent’s old salary with that parent’s current salary.
Income can become one of the most disputed issues in a modification proceeding.
Illinois defines gross income broadly as total income from all sources, subject to statutory exclusions. Net income is then determined using the deductions and tax calculations established by Section 505.
For a parent with traditional W-2 employment, determining income may be relatively straightforward.
Other situations can require closer analysis.
A parent’s earnings may fluctuate significantly from month to month or year to year because of commissions, bonuses, overtime, or other variable compensation.
The financial records may need to be evaluated in context rather than treating one unusually high or low paycheck as representative of ongoing income.
Income can become more complicated when a parent owns a business or is self-employed.
Business revenue is not necessarily the same thing as personal income available for child support purposes. At the same time, business owners may have financial arrangements and expenses that require closer review to determine income under Illinois law.
Accurately documenting financial circumstances can be particularly important when one parent controls the records used to establish his or her earnings.
Changes in parenting time can sometimes affect child support.
Illinois’ child support framework specifically accounts for physical care arrangements, and special calculations can apply when each parent exercises at least 146 overnights per year with the child. Section 505 provides a separate shared-parenting calculation in those circumstances.
This does not mean reaching a particular number of overnights automatically eliminates child support.
The parents’ incomes still matter, as does the specific calculation required under Illinois law.
If the actual parenting arrangement has materially changed, parents may need to consider two separate issues:
Parents seeking to formally change the parenting schedule can review the separate standards governing custody and parenting modifications.
The financial consequences should not drive decisions about parenting time. The parenting arrangement should remain focused on the child’s needs and best interests.
It can.
Child support involves more than the basic monthly support amount. Illinois law also addresses children’s health insurance and health care expenses.
Section 505 allows courts to provide for a child’s current and future medical needs and to allocate qualifying health insurance premiums between parents in proportion to their respective net incomes. Courts may also order contributions toward reasonable health care expenses not covered by insurance, including certain medical, dental, orthodontic, vision, and prescription expenses.
Additionally, 750 ILCS 5/505.2 addresses health insurance provisions when child support is established, modified, or enforced.
A significant change in available insurance or the cost of covering the child may therefore need to be considered during a modification proceeding.
Parents sometimes hear that child support can be modified whenever the new calculation differs from the old amount by 20 percent.
That is an incomplete description of Illinois law.
Section 510 does contain a provision permitting modification without establishing a substantial change when application of the guidelines produces an inconsistency of at least 20 percent and at least $10 per month from the existing order.
However, that provision applies only in cases in which a party is receiving child support enforcement services from the Illinois Department of Healthcare and Family Services under Article X of the Illinois Public Aid Code, and at least 36 months have passed since the support order was entered or last modified. Other statutory limitations also apply.
For parents outside that specific situation, the ordinary substantial-change analysis may apply.
This distinction is important because treating the 20 percent figure as a universal rule can lead parents to misunderstand whether they actually have grounds for modification.
Parents can reach agreements about support, but relying solely on an informal arrangement can create significant problems.
Suppose one parent loses a job and the parents verbally agree that the parent can pay $500 less each month until new employment is found. Even if both parents genuinely intend to cooperate, the existing court order has not necessarily changed. If a dispute develops later, the paying parent may face an argument that the full court-ordered amount remained due.
When parents agree that child support should change, the safer approach is generally to formalize the modification through the appropriate legal process so the court order reflects the new obligation.
A child support modification can become considerably more complicated when the parents disagree about what one of them actually earns.
Concerns may arise when a parent:
Financial documentation can become central in these cases.
Illinois law also provides mechanisms for determining income when reliable information is unavailable. Section 505 permits courts to address situations involving unemployment, underemployment, or insufficient evidence of income according to the statutory standards.
The goal is to establish an accurate financial picture rather than simply accepting a number asserted by either parent.
A parent’s remarriage does not automatically mean child support will increase or decrease.
The child support obligation belongs to the child’s parents. A new spouse does not simply replace either parent’s financial responsibility for the child.
However, remarriage can coincide with other financial or family changes that may become relevant depending on the circumstances.
Parents should therefore avoid assuming that a former spouse’s marriage, by itself, creates an automatic right to modify support.
No.
This is one of the most important practical points for both paying and receiving parents.
A raise does not automatically generate a new child support amount. A job loss does not automatically reduce the payment. A change in parenting time does not automatically rewrite the support order.
Until the support order is properly modified, parents should not assume they are entitled to pay or receive a different amount.
The existing order should be reviewed along with current financial circumstances to determine whether modification is warranted.
Before requesting or responding to a modification, it can help to organize the financial information that shows what has actually changed.
Start with the current child support order and any related judgment or agreement. Understanding how the existing amount was calculated can be important, particularly if the court previously deviated from the guideline amount.
Gather records showing the circumstances that may justify modification.
For an income change, this might include pay records, termination documents, tax returns, employment contracts, or documentation of new compensation.
A modification can require examination of both parents’ current financial circumstances, not simply the finances of the parent requesting the change.
Determine whether anything else affecting the calculation has changed, such as parenting time, health insurance, or qualifying child-related expenses.
Approaching the case with current documentation can make it easier to identify whether the existing order remains appropriate under Illinois law.
There is not a universal rule requiring every parent to wait a fixed number of years before requesting modification based on a substantial change in circumstances. The 36-month provision in Section 510 applies to a specific type of review involving qualifying Department of Healthcare and Family Services cases.
Potentially. A significant reduction in income may support modification, but the court can consider the circumstances surrounding the income change. The existing order does not automatically decrease when earnings fall.
A substantial increase in a parent’s income may be relevant to modification. Because Illinois uses an income shares model, however, the calculation considers both parents’ financial circumstances rather than looking at one parent’s income alone.
Parents can agree that support should change, but an informal agreement does not necessarily modify the existing court order. Formalizing the change helps ensure that the legal obligation matches the parents’ agreement.
A support order may remain in place for years while a family’s finances change considerably. Continuing to rely on an outdated calculation can create problems for either parent, particularly when income, parenting arrangements, or a child’s financial needs have materially changed.
The important question is not simply whether your circumstances are different. It is whether the change satisfies Illinois’ requirements for modification and what the support obligation should be under the current facts.
Keller Legal Services represents parents seeking increases and reductions in child support, as well as parents responding to modification requests, throughout Naperville, DuPage County, Kane County, Will County, and surrounding Illinois communities.
Call 630-505-1515 to schedule a free consultation and discuss whether your existing child support order should be reviewed or modified under Illinois law.
