How is Child Support Calculated?

Find out how Illinois calculates and figures out child support

Frequently asked:

how is child support calculated in illinois?

To establish a child support order in Illinois, the amount of child support considered for the order depends on the non-custodial parent's net income and the number of children for which he or she is responsible. The chart below represents the minimum of what may be ordered according to the Illinois Statutory Guidelines (750 ILCS 5/505 Sec. 505).

Statutory Guidelines of Child Support

Number of ChildrenPercent of Non-Custodial Parent's Net Income

1                             20%

2                         28%

3                         32%

4                         40%

5                             45%

6 or more              50%

The guidelines in the chart are applied to each case unless the court makes a finding that the amount determined in the guidelines would be inappropriate after considering the best interests of the child. Relevant factors for deviations may include but are not limited to:

  • The financial resources and needs of the child(ren);
  • The financial resources and needs of the custodial parent;
  • Standard of living the child(ren) would have enjoyed had the marriage not been dissolved, the separation not occurred, or if the parties had married;
  • The physical and emotional condition of the child(ren) and their educational needs; and
  • The financial resources and needs of the non-custodial parent.

Net income is the total of all income from all sources, minus the following deductions:

  • Federal income tax;
  • State income tax;
  • Social Security (FICA);
  • Mandatory retirement contributions;
  • Union dues;
  • Dependent and individual health/hospitalization insurance premiums;
  • Prior obligations of support or maintenance actually paid pursuant to a court order or administrative order;
  • Expenses to repay debts that represent reasonable and necessary expenses for the production of income;
  • Medical expenses necessary to preserve life or health; and
  • Reasonable expenses for the benefit of the child and the other parent, exclusive of gifts.
  • In 2016, the law has changed to include Student Loans.

If net income cannot be determined, the court shall order support in an amount considered reasonable in the particular case.

If net income cannot be determined in administrative cases, the Department uses a standard amount based on the state’s minimum wage to arrive at the monthly support obligation. The Department is given the authority to establish support through an administrative process. Support orders established through this process have the same force and effect as a judicial order. (45 CFR 300.0 or 89 IL Administrative Code, Sec. 160.60 or 305 ILCS 5/Art. X).

Calculating Child Support Obligation Form

To calculate a minimum child support order, fill in the Calculating Child Support Obligation Form (pdf).

Prior Obligations of Support or Maintenance

Note: IL case law (Potts vs. Potts) 297 Ill. App 3d 110, 696 N.E. 2nd 1263, 231 Ill. Dec. 692 (1998) determined that prior obligations of support or maintenance actually paid pursuant to a court order is a specified deduction. Prior obligations mean the family that is first in time, not the support order that is entered first. If the NCP’s pay does not allow all payments to be deducted due to the federal Consumer Credit Protection Act, the employer must prorate allocating a percentage to each order based on the total dollar amount of current support ordered.