What is the legal standard for deviating from guideline child support in Illinois?

Under 750 ILCS 5/505(a)(2), the court may deviate from the guideline amount if it finds that application of the guideline would be "unjust or inappropriate." The guideline amount is presumed to be correct, and the party seeking deviation bears the burden of proving that the presumption should be overcome based on the statutory factors.

What factors can Illinois courts consider when deviating from the guideline?

Illinois statute specifies six primary factors: (1) financial resources and needs of both parents, (2) standard of living the child would have enjoyed, (3) physical, emotional, and educational condition/needs of the child, (4) physical and financial condition of the non-custodial parent, (5) educational opportunities for the child, and (6) any other factor the court finds relevant to the child's best interests.

Can a parent request a deviation due to children from other relationships?

Illinois law allows consideration of children from other relationships, but the impact is already incorporated into the net income calculation through deductions for prior court-ordered support. Courts rarely grant additional deviations for this reason unless there are extraordinary circumstances beyond the standard multi-family adjustment.

How do special needs of a child affect deviation requests?

Special needs—whether physical, emotional, mental, or educational—are explicitly listed as a deviation factor under 750 ILCS 5/505(a)(2)(c). If a child requires therapy, specialized education, medical equipment, or other documented special needs services beyond what's captured in the guideline amount, courts may grant an upward deviation.

Can Illinois courts deviate from the guideline for high-income earners?

Yes. The Illinois Schedule of Basic Child Support Obligations caps at certain income levels. For combined incomes beyond the schedule, courts have discretion to determine an appropriate support amount. The deviation may be upward or downward depending on the child's actual needs and lifestyle considerations.

What documentation is needed to support a deviation request?

Documentation varies by the basis for deviation but typically includes: complete Financial Affidavits, tax returns (2-3 years), pay stubs, expense records, medical/therapy bills, educational assessments, proof of extraordinary expenses, and expert reports (if applicable). The more detailed and verifiable the documentation, the stronger the case.

Are deviation orders permanent?

No. Like all child support orders, deviation orders remain modifiable if there is a substantial change in circumstances. Either parent can petition for modification if financial situations change, the child's needs evolve, or the factors justifying the original deviation no longer apply.

Can I appeal a court's decision to grant or deny a deviation?

Yes. Either parent has the right to appeal a trial court's decision on deviation, whether it grants, denies, or modifies the guideline amount. The appellate court will review whether the trial court properly applied the statutory factors and whether its findings are against the manifest weight of the evidence.

Deviation Factors750 ILCS 5/505(a)(2)

Illinois Child Support Deviation Factors

When and how Illinois courts can deviate from guideline child support calculations based on statutory factors and extraordinary circumstances.

Calculate Guideline Support Formula Guide

Quick Facts

Legal Basis

750 ILCS 5/505

Statutory deviation factors

750 ILCS 5/505(a)(2)

Standard Required

High Bar

Unjust or Inappropriate

Must show guideline would be improper

750 ILCS 5/505(a)(2)

Burden of Proof

Party Seeking Deviation

Must present evidence and legal argument

750 ILCS 5/505(a)(2)

Written Findings

Required

Mandatory

Court must explain deviation reasons

750 ILCS 5/505(a)(2)

Guideline Presumption

Rebuttable

Guideline amount is presumed correct

750 ILCS 5/505(a)(1.5)

Appeal Rights

Both Parties

Deviation orders are reviewable

Illinois Supreme Court Rule 303

Understanding Deviation from Guideline Support

While Illinois law establishes a guideline child support amount through the income shares model (750 ILCS 5/505), courts recognize that no single formula can account for every family's unique circumstances. The statute allows judges to deviate from the guideline when application would be "unjust or inappropriate."

The guideline amount is presumed correct. This means the party seeking a different amount—whether higher or lower—bears the burden of proving the presumption should be overcome. Courts must issue written findings explaining any deviation.

Important: Deviation is the exception, not the rule. Most child support orders follow the guideline calculation. Successful deviation requires strong evidence and clear legal arguments based on the statutory factors.

Statutory Deviation Factors

Illinois law specifies the following factors courts must consider when evaluating deviation requests:

Financial Resources and Needs

Financial resources and needs of both the custodial and non-custodial parent

Legal Basis:

750 ILCS 5/505(a)(2)(a)

Example:

Parent has significant debt obligations, major medical expenses, or extraordinary income fluctuations

Notes:

Court considers each party's ability to pay and the child's actual needs

Standard of Living

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

Legal Basis:

750 ILCS 5/505(a)(2)(b)

Example:

Child previously lived in high-income household with private education and extensive activities

Notes:

Aims to maintain consistency in child's lifestyle where possible

Physical and Emotional Condition

Physical, emotional, and mental condition of the child and their educational needs

Legal Basis:

750 ILCS 5/505(a)(2)(c)

Example:

Child has special needs requiring therapy, specialized education, or medical equipment

Notes:

May justify upward deviation for documented special needs

Parents' Physical and Financial Condition

The physical, mental, and financial condition and needs of the non-custodial parent

Legal Basis:

750 ILCS 5/505(a)(2)(d)

Example:

Parent has disability limiting earning capacity or extraordinary medical expenses

Notes:

Can justify downward deviation if parent genuinely cannot pay guideline amount

Educational Opportunities

Educational opportunities for the child beyond high school

Legal Basis:

750 ILCS 5/505(a)(2)(e)

Example:

Parent requests deviation to establish college savings fund or pay private school tuition

Notes:

Illinois allows consideration of post-secondary education costs

Reasonable and Necessary Expenses

Expenses for production of income and debts reasonably necessary for the production of income

Legal Basis:

750 ILCS 5/505(a)(3)(h)

Example:

Self-employed parent has significant business loan payments required for income generation

Notes:

Must demonstrate expenses directly enable income production

Best Interests of Child

Any other factor the court expressly finds to be relevant in the best interest of the child

Legal Basis:

750 ILCS 5/505(a)(2)(f)

Example:

Unique family circumstances not covered by other statutory factors

Notes:

Catch-all provision allowing court discretion for unusual situations

Procedure for Requesting Deviation

File Petition or Motion

Submit formal request to deviate from guideline with supporting affidavit

Required Documents:

Petition or Motion to Deviate, Financial Affidavit, Income/Expense Documentation

Timing:

With initial petition or as post-judgment motion

Prepare Legal Argument

Draft memorandum citing 750 ILCS 5/505(a)(2) and explaining why guideline is unjust/inappropriate

Required Documents:

Memorandum of Law, supporting case citations

Timing:

Filed with motion or before hearing date

Gather Supporting Evidence

Compile financial records, medical documentation, educational reports as applicable

Required Documents:

Tax returns, pay stubs, medical bills, special needs assessments, tuition invoices

Timing:

Submitted with motion or via discovery

Serve Other Parent

Proper service of all documents on opposing party per Illinois Supreme Court Rules

Required Documents:

All filed documents + Certificate of Service

Timing:

Minimum 30 days before hearing for petitions

Attend Hearing

Present evidence and testimony explaining why guideline amount is unjust or inappropriate

Required Documents:

Witness list, exhibits, prepared testimony outline

Timing:

Scheduled hearing date

Court Issues Findings

Judge must issue written findings explaining reason for deviation (if granted)

Required Documents:

Court Order with specific findings of fact and conclusions of law

Timing:

Within reasonable time after hearing (typically 30-60 days)

Common Deviation Scenarios

Upward Deviations

When might support increase above guideline?

Child has documented special needs requiring costly therapy or equipment
Private school tuition deemed appropriate given family history
Payor's income far exceeds schedule maximum
Child requires medical care beyond basic insurance

Downward Deviations

When might support decrease below guideline?

Payor has disability limiting earning capacity
Payor faces extraordinary mandatory debt obligations
Shared physical care costs not fully captured by 1.5x multiplier
Payee has substantial independent wealth or assets

Frequently Asked Questions

Related Resources

Illinois Child Support Calculator

Calculate guideline support amount before considering deviations

Child Support Formula Guide

Understand the income shares calculation methodology

Child Support Modification

Learn how to modify an existing support order

How to File for Child Support

Step-by-step guide to establishing a support order

References & Accuracy

Editorial Review

Last Reviewed: January 15, 2025

Next Review: July 15, 2025

Reviewed By: TheDivorceCalc Editorial Team

Primary Legal Sources

statute750 ILCS 5/505 – Child support calculation and deviation factors
statute750 ILCS 5/504 – Maintenance (spousal support) provisions
officialIllinois HFS Income Shares – Official guidelines and worksheets

Internal Research: This page incorporates analysis of Illinois case law regarding child support deviations and statutory interpretation of 750 ILCS 5/505. For additional context, see our Formula Guide and Calculator.

Accuracy Statement: We update this content semi-annually to reflect changes in Illinois family law. Deviation determinations are highly fact-specific and discretionary. This information is for educational purposes and does not constitute legal advice. For case-specific guidance, consult a licensed Illinois family law attorney.