Child Support in Illinois

Find out how child support is calculated in Illinois.

Both parents, whether married to one another or not, must support their children. Most states have specific rules for calculating the financial responsibilities of single, separated, or divorced parents, and for ensuring that parents pay support. Although parents can enter into agreements about child support, such agreements must, at a minimum, meet the guidelines set by law and receive court approval. This is because the right to receive support belongs to the child - not the parents.

Calculating Child Support in Illinois

The State of Illinois has set child support guidelines, which courts must follow to determine the amount of child support one parent must pay the other. Illinois calculates basic support as a percentage of a non-custodial parent’s net income, after allowing for certain deductions. The percentage increases according to the number of children, as follows:

  • 20% for one child
  • 28% for two children
  • 32% for three children
  • 40% for four children
  • 45% for five children, and
  • 50% for six or more children.

Adjustments to the Formula

The Illinois child support formula is one of the oldest and simplest in the country. Most states have changed their formulas to consider the relative incomes of both parents, as well as the amount of time a child spends with each parent. The Illinois formula may change in the future as well. But, in the meantime, judges in Illinois can make adjustments if the guideline amount doesn’t adequately address a child’s best interests in light of all relevant factors, including:

  • the child’s probable standard of living had the parents stayed together
  • the child’s physical and emotional condition
  • the child’s educational needs, and
  • the financial resources and needs of the child and both parents.

The guideline percentages are based on a traditional custody arrangement, where a non-custodial parent has visitation every other weekend and for up to several weeks during the summer. The court is likely to deviate from the guidelines if parents are exercising joint or shared physical custody, or if a non-custodial parent’s visitation time goes beyond the traditional arrangement. In an appropriate case, a court may also add expenses to the guideline amount for items, such as daycare, health care, extracurricular activities, or private school tuition. And, a very high-income parent may be able to pay more than the guideline amount, while a very low-income parent may pay less.

Calculating Net Income for Child Support

To calculate child support in Illinois, you’ll need to add up the non-custodial parent’s available “net income.” This includes all income, whether earned or unearned, minus any applicable deductions and adjustments listed in the guidelines. Common examples of income are wages, commissions, self-employment earnings, and investment income. Deductions include federal and state income taxes, social security tax, mandatory retirement contributions, union dues, health insurance premiums for the non-custodial parent or dependents, expenses necessary to produce income, medical expenses necessary for life or health, and any reasonable amounts already paid for the benefit of the child or the custodial parent, not including gifts. The non-custodial parent can also deduct any court-ordered alimony (spousal support) or child support previously paid.

Parents can calculate a minimum support order by completing a Child Support Obligation Form, available from The Illinois Department of Healthcare and Family Services Division of Child Support Services (DCSS). DCSS is the state agency responsible for helping families obtain child support payment orders, locate absent parents, establish paternity if necessary, and secure compliance with child support orders. You can find more information about DCSS services for both custodial and non-custodial parents on their website.

Imputing Income

Even if you don’t have any income, you could still be responsible for child support. If a court believes a parent is voluntarily unemployed or “underemployed” (working at a lower paying job than qualified for, or working fewer hours than the parent is able to work), the judge will look carefully at the reasons for the lack of income.

Unless the parent shows evidence of serious job-hunting efforts or disability, a judge might base support on “imputed” (potential) income. Imputed income can be based on a parent's most recent job or on local job opportunities that the parent would qualify for based on training and experience. If there is no evidence of greater earning ability, a court will probably impute income at minimum wage.

(To learn more about imputed income, see our article, "Imputing Income for Child Support").

Termination or Modification of Child Support

A parent seeking modification of an existing support order must show an ongoing material change in circumstances. In Illinois, the obligation to support a child ends when the child turns 18, unless the child is still attending high school full-time, in which case it continues until the child turns 19 or graduates from high school, whichever happens first. The obligation may continue beyond this if a child is disabled and not capable of self-support. Judges in Illinois also sometimes order a non-custodial parent to help with the expenses of a child over 19 that is attending college.

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