Illinois Family Law Guide
Income Shares • Maintenance • Custody • Procedure
Income Shares Child Support
Shared parenting credits, add-on reimbursements, and maintenance sequencing.
Run Child Support →Guideline Maintenance
Applicability test, 33⅓% – 25% formula, 40% cap, and duration projection.
Estimate Maintenance →Child Support (750 ILCS 5/505)
Illinois adopted the Income Shares model in 2017. The process starts with each parent’s monthly net income, applies the HFS Basic Child Support Obligation schedule, and adjusts for shared parenting and add-on costs. Maintenance must be calculated first because it changes each parent’s net income.
Calculate combined monthly net income, locate the Basic Child Support Obligation (BCSO) on the HFS schedule, and prorate by each parent’s income share.
When each parent has at least 146 nights, increase the BCSO by 50% and apply cross-credit to reflect duplicated household costs.
Work-related childcare, children’s healthcare premiums, and extraordinary expenses are allocated in proportion to income share.
Courts may reduce the order if the obligor’s net income would fall below poverty-level benchmarks.
Spousal Maintenance (750 ILCS 5/504)
Guideline maintenance is a starting point. Courts must still consider the statutory factors in 750 ILCS 5/504(a). When guidelines apply, use the 33⅓% – 25% calculation, enforce the 40% cap, and project duration via the statutory multiplier table.
33⅓% of the payor’s net income minus 25% of the payee’s net income, available when combined gross income is under $500,000 and the payor has no prior obligations.
Reduce the maintenance award if the payee would exceed 40% of combined net income after the transfer.
Multiply years of marriage by statutory multipliers (0.20 – 0.80). Marriages of 20+ years may be indefinite or match the marriage length.
Custody & Parenting Time Factors
Illinois courts allocate decision-making responsibility and parenting time based on the child’s best interests (750 ILCS 5/602.5 & 602.7). Parenting plans should address transportation, communication, school breaks, and dispute resolution.
- Child’s adjustment to home, school, and community
- Each parent’s willingness to foster the child’s relationship with the other
- History of caregiving and involvement
- Mental and physical health of all parties
- Presence of domestic violence or abuse
- Relocation proposals and impact on the child
Key Procedural Milestones
Filing a Petition for Dissolution triggers Automatic Temporary Restraining Provisions prohibiting asset dissipation, insurance changes, and relocation with the child without consent or court order.
Parties must exchange a Financial Affidavit, recent tax returns, pay stubs, and statements within 30 days of service or appearance.
Most circuits require completion of a parenting education program within 60 days of filing when minor children are involved.
Support or maintenance may be modified upon a substantial change in circumstances. Maintenance terminates upon remarriage, cohabitation, or death.
Essential Resources
When to Consult Counsel
Seek legal counsel promptly if your case involves business valuation, relocation, complex parenting disputes, or potential deviations from guidelines. Illinois’ statutory factors provide broad discretion, and tailored advice ensures your financial plan aligns with court expectations.
The Illinois State Bar Association and local county bar associations maintain referral programs. For low-income litigants, review the Illinois Legal Aid Online directory and circuit court self-help centers.