Illinois child support and custody laws work through two separate frameworks. Custody is handled under the “allocation of parental responsibilities,” which splits significant decision-making authority from parenting time and assigns each based on the child’s best interests. Child support is calculated under an income-shares model that combines both parents’ net incomes and divides the resulting obligation proportionally. Both sets of rules sit in the Illinois Marriage and Dissolution of Marriage Act, 750 ILCS 5.
How Custody Works in Illinois
Illinois no longer uses the word “custody” in its statute. The law instead divides parental rights into two categories: significant decision-making responsibility and parenting time.1Illinois General Assembly. Illinois Code 750 ILCS 5/600 – Definitions Decision-making covers education, healthcare, religion, and extracurricular activities. A court can give one parent sole authority over all of those areas, split them between parents, or require the parents to agree jointly on each one.
When parents cannot work it out, a judge decides based on the child’s best interests. The statute lists more than a dozen factors for allocating decision-making, including each parent’s willingness to cooperate, the child’s own wishes weighted by maturity, the child’s relationship with each parent and with siblings, and any history of physical violence or abuse in the household.2Illinois General Assembly. Illinois Code 750 ILCS 5/602.5 – Allocation of Parental Responsibilities Decision-Making A parent’s status as a sex offender is an explicit factor. So is whether either parent has tried to undermine the child’s relationship with the other parent.
Parenting time uses a related but separate list of best-interests factors. Courts look at how much day-to-day caregiving each parent handled in the two years before the case was filed, the distance between the parents’ homes, the child’s adjustment to school and community, and the mental and physical health of everyone involved.3Illinois General Assembly. Illinois Code 750 ILCS 5/602.7 – Allocation of Parenting Time If parents agree, they submit a written parenting plan for court approval. If they cannot, the court builds the schedule using these statutory factors.
In contested cases, courts may appoint a guardian ad litem, who investigates and makes recommendations to the judge, or a child representative, who acts as the child’s lawyer and advocates for the child’s best interests rather than the child’s stated preferences. Judges can also order mediation or psychological evaluations.
When Parenting Time Gets Restricted
If a parent’s conduct has seriously endangered a child’s physical, mental, or emotional well-being, the court can restrict that parent’s time and decision-making. Available restrictions include supervised visitation, requiring exchanges through an intermediary or at a protected location, ordering drug or alcohol abstinence during parenting time, and prohibiting specific people from being present during visits.4Justia Law. Illinois Code 750 ILCS 5 Part VI – Allocation of Parental Responsibilities – Section 603.10 The court must find by a preponderance of the evidence that the parent’s behavior warrants these limits. Restrictions can be modified later if circumstances change.
Moving With a Child
A parent who wants to move with a child has to follow notice rules that depend on where the move goes. Illinois defines a qualifying “relocation” as a move of more than 25 miles from the child’s current home if the family lives in Cook, DuPage, Kane, Lake, McHenry, or Will County; more than 50 miles if in any other Illinois county; or more than 25 miles to a location outside the state.1Illinois General Assembly. Illinois Code 750 ILCS 5/600 – Definitions
The relocating parent has to give the other parent at least 60 days’ written notice before the move, stating the intended date, the new address if known, and whether the move is permanent or temporary. If the other parent signs the notice, the move can go forward without a hearing, and the court modifies the parenting plan accordingly. If the other parent objects or refuses to sign, the relocating parent must file a petition asking the court for permission. A court can treat failure to provide proper notice as evidence of bad faith and may award attorney’s fees to the other parent.5Illinois General Assembly. Illinois Code 750 ILCS 5/609.2 – Relocation
How Child Support Is Calculated
Illinois uses the income-shares model. It estimates what parents would have spent on the child if they still lived together, then splits that amount proportionally based on each parent’s share of their combined net income.6Illinois General Assembly. Illinois Code 750 ILCS 5/505 – Child Support, Contempt, Penalties The Illinois Department of Healthcare and Family Services publishes a schedule of basic support obligations keyed to combined income and number of children. Courts plug both parents’ net incomes into that schedule to find the baseline obligation, then assign each parent a percentage.
Gross income means income from all sources, with a few exceptions: means-tested public assistance such as TANF and SNAP, and benefits received for other children in the household such as foster care payments or child support for a different child. Social Security disability or retirement benefits paid on behalf of the child count toward the disabled or retired parent’s obligation, though that parent gets a credit for amounts paid directly to the other household.6Illinois General Assembly. Illinois Code 750 ILCS 5/505 – Child Support, Contempt, Penalties Net income comes from subtracting standardized or individualized tax amounts and other permitted adjustments.
If a parent is voluntarily unemployed or underemployed, the court can impute income based on earning potential. That requires an evidentiary hearing (or both parties’ agreement) and written findings. The court considers the parent’s work history, job skills, education, health, criminal record, and local job market. When there is not enough work history to gauge earning potential, there is a rebuttable presumption that the parent could earn at least 75% of the federal poverty guidelines for a single person. Incarceration does not count as voluntary unemployment.6Illinois General Assembly. Illinois Code 750 ILCS 5/505 – Child Support, Contempt, Penalties
Child support is tax-neutral under federal law. The paying parent cannot deduct it, and the receiving parent does not report it as income.7Internal Revenue Service. Dependents 6
When Support Ends and College Expenses
Support obligations normally end when the child turns 18, or at 19 if the child is still finishing high school.6Illinois General Assembly. Illinois Code 750 ILCS 5/505 – Child Support, Contempt, Penalties The termination date does not wipe out arrears that have accumulated.
A separate statute lets courts order either or both parents to contribute to college and post-secondary expenses. That includes tuition and fees (capped at the in-state cost of the University of Illinois at Urbana-Champaign), housing (capped at double-occupancy dorm rates at the same university), and books. These educational expense orders can run until the student turns 23, or in exceptional cases up to age 25.8Illinois General Assembly. Illinois Code 750 ILCS 5/513 – Educational Expenses for a Non-Minor Child
Changing an Existing Order
A child support order is not permanent. Either parent can petition to modify it by showing a substantial change in circumstances, such as a job loss, a significant raise, or a change in the child’s needs. The court will not deny a modification just because the change was foreseeable when the original order was entered, unless the order specifically says otherwise.9Illinois General Assembly. Illinois Code 750 ILCS 5/510 – Modification of Judgments
In cases where the state’s child support enforcement agency is involved, a parent can also seek modification without proving changed circumstances if the current order differs from what the guidelines would produce by at least 20% and at least $10 per month. This administrative review option becomes available once 36 months have passed since the order was entered or last modified.9Illinois General Assembly. Illinois Code 750 ILCS 5/510 – Modification of Judgments
What Happens When a Parent Doesn’t Pay
When a parent falls behind, Illinois has several enforcement tools. The state can intercept tax refunds, place administrative liens on bank accounts, and suspend driver’s licenses for nonpayment.10Illinois Department of Healthcare and Family Services. Information for Non-Custodial Parents Courts can hold a delinquent parent in contempt, which can result in fines or jail time. Wage withholding is the default collection method for most orders.
When Parents Live in Different States
If one parent moves out of state, two uniform laws control what happens. For custody, the Uniform Child-Custody Jurisdiction and Enforcement Act (UCCJEA) gives priority to the child’s “home state,” meaning where the child has lived for at least six consecutive months before the case is filed. If no state qualifies, the UCCJEA looks at which state has the most significant connection to the child and the most available evidence about the child’s life.11Illinois General Assembly. Illinois Code 750 ILCS 36/201 – Initial Child-Custody Jurisdiction Physical presence alone is not enough to give a state jurisdiction.
For support, the Uniform Interstate Family Support Act (UIFSA) keeps exclusive authority over an existing order with the state that issued it, as long as one of the parties or the child still lives there. A parent cannot escape an Illinois support order by moving to another state. UIFSA also provides cross-state wage garnishment, and every state has a central registry office that processes interstate support petitions.