In Illinois, alimony (called maintenance) and child support serve fundamentally different purposes and follow completely separate calculation methods. Maintenance under 750 ILCS 5/504 provides financial support to a lower-earning spouse using a formula of 33.33% of the payor's net income minus 25% of the recipient's net income. Child support under 750 ILCS 5/505 covers children's basic needs using the income shares model, which combines both parents' incomes to determine the total support obligation. Understanding the difference between alimony and child support in Illinois is essential for anyone navigating divorce, as these two obligations affect your finances differently for years after your marriage ends.
Key Facts: Illinois Divorce Overview
| Category | Details |
|---|---|
| Filing Fee | $210-$388 (varies by county; Cook County charges $388) |
| Residency Requirement | 90 days in Illinois before filing under 750 ILCS 5/401 |
| Waiting Period | None if both parties agree; 6 months separation if contested |
| Grounds for Divorce | No-fault only (irreconcilable differences) since 2016 |
| Property Division | Equitable distribution under 750 ILCS 5/503 |
| Maintenance Formula | 33.33% payor net income - 25% recipient net income |
| Child Support Model | Income shares (combined parental income approach) |
What Is the Difference Between Alimony and Child Support in Illinois?
Alimony (maintenance) and child support in Illinois differ in recipient, purpose, calculation method, duration, and tax treatment. Maintenance payments go directly to a former spouse to help maintain their standard of living, while child support payments benefit the children and are managed by the custodial parent. Under 750 ILCS 5/504, maintenance is calculated using a statutory formula based on the difference between spouses' incomes, with the recipient capped at receiving no more than 40% of combined net income. Child support under 750 ILCS 5/505 uses the income shares model, which bases the obligation on what parents would have spent on the child if the household had remained intact.
The fundamental distinction lies in who the payment protects. Maintenance addresses spousal dependency that developed during the marriage, particularly when one spouse sacrificed career advancement to support the household or raise children. Child support ensures children maintain access to both parents' financial resources regardless of which parent they primarily live with. Illinois courts treat these as entirely separate obligations, and receiving one does not affect eligibility for the other.
How Is Spousal Maintenance Calculated in Illinois?
Illinois calculates maintenance using a statutory formula under 750 ILCS 5/504: 33.33% of the payor's net income minus 25% of the recipient's net income, with a cap ensuring the recipient cannot receive more than 40% of combined net income. This formula applies to couples with combined gross income under $500,000 annually. For example, if the paying spouse earns $120,000 net annually and the receiving spouse earns $40,000 net annually, maintenance would be $29,996 annually ($120,000 × 0.3333 = $39,996 minus $40,000 × 0.25 = $10,000).
Illinois courts consider 14 statutory factors when determining whether to award maintenance, including:
- Each party's income and property
- Each party's needs
- Each party's present and future earning capacity
- Any impairment of earning capacity due to domestic duties or educational delays
- Time needed for the recipient to acquire education or training
- The standard of living established during the marriage
- Duration of the marriage
- Age, physical, and emotional condition of both parties
- Tax consequences to each party
- Contributions to the other spouse's education or career
- Any valid prenuptial or postnuptial agreement
- Either party's sacrifices for the marriage
- Any other relevant factors
The duration of maintenance directly corresponds to the length of the marriage through statutory multipliers. For marriages lasting 5-6 years, the duration multiplier is 0.24; for 10-11 years, it rises to 0.44; for 15-16 years, it reaches 0.64. Marriages lasting 20 years or more may result in indefinite maintenance at the court's discretion. A 10-year marriage would typically result in maintenance lasting 4.4 years (10 × 0.44 = 4.4 years).
How Is Child Support Calculated in Illinois?
Illinois uses the income shares model under 750 ILCS 5/505, which combines both parents' net incomes and applies a basic support obligation based on the number of children. Both parents' gross incomes from all sources are combined, then each parent's proportional share determines their contribution to the total obligation. For two children with combined parental net income of $150,000 annually, the basic support obligation from Illinois guidelines might be approximately $2,400 monthly, split proportionally between parents based on their income percentages.
The income shares model includes income from all sources:
- Wages, salaries, and commissions
- Bonuses and overtime pay
- Self-employment earnings
- Pensions and Social Security benefits
- Unemployment and disability payments
- Rental income and investment returns
- Trust and annuity income
Additional child-related expenses are typically allocated in proportion to each parent's income share, including:
- Health insurance premiums for the child
- Unreimbursed medical expenses
- Childcare costs necessary for employment or education
- Educational expenses as agreed or ordered
Illinois updated its child support guidelines effective March 5, 2025, with revised gross-to-net income conversion tables and updated basic support obligation schedules. The state conducts quadrennial reviews of these guidelines, with the next review scheduled for 2026. When parents share physical custody (defined as 146 or more overnights annually with the child, equaling 40% parenting time), the shared parenting formula multiplies the basic obligation by 1.5 before calculating each parent's share.
Comparison Table: Alimony vs. Child Support in Illinois
| Factor | Maintenance (Alimony) | Child Support |
|---|---|---|
| Recipient | Former spouse | Child (through custodial parent) |
| Governing Statute | 750 ILCS 5/504 | 750 ILCS 5/505 |
| Calculation Method | 33.33% payor minus 25% recipient | Income shares (combined parental income) |
| Income Cap | Applies to combined gross under $500,000 | No cap; guidelines cover all income levels |
| Duration | Marriage length × statutory multiplier | Until child turns 18 (or 19 if still in high school) |
| Tax Treatment (Federal) | Not deductible/not taxable (post-2018) | Not deductible/not taxable |
| Modification | Substantial change in circumstances | Substantial change in circumstances |
| Termination Events | Remarriage, cohabitation, or death | Child's emancipation, adoption, or death |
| Court Discretion | Significant (14 factors considered) | Limited (guidelines create rebuttable presumption) |
Tax Implications: Which Is More Tax-Efficient?
Neither alimony nor child support provides tax advantages under current federal law. The Tax Cuts and Jobs Act of 2017 eliminated the alimony tax deduction for divorce agreements executed after December 31, 2018, meaning the paying spouse cannot deduct maintenance payments and the receiving spouse does not report them as taxable income. Illinois conforms to federal tax treatment, so neither party claims any state tax benefit from maintenance payments. Child support has never been tax-deductible for the payor or taxable to the recipient under federal or Illinois law.
For divorces finalized before January 1, 2019, the prior tax rules may still apply. Under pre-2019 agreements, the paying spouse could deduct alimony payments, and the receiving spouse reported them as taxable income. Couples with older divorce decrees should consult a tax professional to determine which rules govern their situation. Modifications to pre-2019 agreements may preserve the original tax treatment unless the modification explicitly states that the new tax rules apply.
Duration: How Long Do These Payments Last?
Maintenance duration in Illinois follows statutory guidelines tied directly to the length of the marriage under 750 ILCS 5/504(b-1). A marriage lasting 8-9 years uses a 0.36 multiplier, meaning maintenance would last approximately 3.24 years (9 years × 0.36). For marriages lasting 20 years or longer, courts have discretion to order maintenance for a period equal to the marriage length or for an indefinite term. Maintenance terminates automatically upon the recipient's remarriage, death of either party, or the recipient's cohabitation with another person in a conjugal relationship.
Child support obligations continue until the child reaches age 18 under Illinois law, or age 19 if the child is still attending high school. Courts may order support beyond these ages for children with disabilities or to cover post-secondary educational expenses. Unlike maintenance, child support does not terminate upon either parent's remarriage, though it does end upon the child's legal emancipation, adoption by another person, or the child's marriage.
The duration multipliers for maintenance in Illinois are:
| Marriage Length | Multiplier | Example Duration |
|---|---|---|
| Less than 5 years | 0.20 | 4 years × 0.20 = 0.8 years |
| 5-6 years | 0.24 | 6 years × 0.24 = 1.44 years |
| 10-11 years | 0.44 | 11 years × 0.44 = 4.84 years |
| 15-16 years | 0.64 | 16 years × 0.64 = 10.24 years |
| 20+ years | Indefinite or equal to marriage length | Court discretion |
Can You Receive Both Alimony and Child Support?
Yes, Illinois courts can award both maintenance and child support simultaneously when circumstances warrant both types of support. A lower-earning spouse with primary custody of minor children may receive maintenance for personal financial needs and child support for the children's expenses. The two obligations serve different purposes and are calculated independently, though courts consider both when evaluating each party's overall financial position. Receiving child support does not reduce eligibility for maintenance, and receiving maintenance does not reduce child support entitlement.
When calculating both obligations, Illinois courts determine child support first using the income shares guidelines, then calculate maintenance based on net incomes. The maintenance formula (33.33% minus 25%) and the 40% cap apply after accounting for child support obligations. This ordering ensures child support takes priority, reflecting Illinois policy that children's needs come before spousal support.
Modification and Enforcement in Illinois
Both maintenance and child support can be modified upon showing a substantial change in circumstances under Illinois law. Job loss, significant income changes, disability, or retirement may justify modification of either obligation. For maintenance, courts also consider changes in either party's living arrangements, health status, or economic position. Child support modifications may be requested when either parent's income changes by 20% or more, when healthcare costs change substantially, or when parenting time arrangements shift significantly.
Illinois enforces both obligations through the same mechanisms:
- Income withholding orders (mandatory for all support orders)
- Interception of tax refunds
- Suspension of driver's licenses, professional licenses, and recreational licenses
- Contempt of court proceedings (can result in jail time)
- Credit bureau reporting
- Passport denial for arrears exceeding $2,500
- Liens on real and personal property
The Illinois Department of Healthcare and Family Services (HFS) Division of Child Support Services handles enforcement of child support orders, while maintenance enforcement typically requires private legal action. Arrearages for both maintenance and child support accumulate interest at the statutory rate of 9% annually under 735 ILCS 5/2-1303 and cannot be discharged in bankruptcy.
Which Is More: Alimony or Child Support?
The answer depends entirely on each family's income levels, number of children, and marriage duration. For a couple with combined net income of $200,000 and two children, child support under Illinois guidelines might total $35,000-$45,000 annually, while maintenance for a 10-year marriage might be $20,000-$30,000 annually. However, for a childless couple with significant income disparity after a 20-year marriage, maintenance could substantially exceed what child support would be for families with children. Neither payment is inherently larger than the other.
Factors affecting relative amounts include:
- Number of children (more children = higher child support)
- Income disparity between spouses (greater disparity = higher maintenance)
- Marriage length (longer marriage = longer maintenance duration)
- Parenting time allocation (shared custody reduces child support)
- Each party's earning capacity and employment history
Filing for Divorce in Illinois: What You Need to Know
Filing for divorce in Illinois requires meeting the 90-day residency requirement under 750 ILCS 5/401, meaning at least one spouse must have lived in Illinois for 90 consecutive days before filing. Filing fees range from $210 to $388 depending on the county, with Cook County charging $388 for the petitioner. Illinois is a no-fault state, so irreconcilable differences is the only ground for divorce since 2016 under Public Act 99-90. If both parties agree the marriage is irretrievably broken, no waiting period applies; if one party contests the divorce, a 6-month separation period creates an irrebuttable presumption of irreconcilable differences.
Illinois uses equitable distribution under 750 ILCS 5/503 to divide marital property, meaning assets are divided fairly but not necessarily equally. Marital property includes most assets and debts acquired after marriage and before the divorce filing, while non-marital property (assets owned before marriage, inheritances, and gifts) remains with the original owner. Courts consider 12 statutory factors when determining equitable distribution, including marriage length, each spouse's contributions, and economic circumstances after divorce.
Frequently Asked Questions
What is the difference between alimony and child support in Illinois?
Alimony (maintenance) supports a former spouse while child support covers children's needs. Under 750 ILCS 5/504, maintenance equals 33.33% of the payor's net income minus 25% of the recipient's net income. Child support under 750 ILCS 5/505 uses the income shares model, combining both parents' incomes to determine obligations proportionally.
How is spousal maintenance calculated in Illinois for 2026?
Illinois calculates maintenance as 33.33% of the payor's net income minus 25% of the recipient's net income, capped so the recipient receives no more than 40% of combined net income. This formula applies to couples with combined gross income under $500,000 annually. Duration depends on marriage length using statutory multipliers ranging from 0.20 for marriages under 5 years to indefinite for marriages of 20+ years.
Is alimony tax deductible in Illinois?
No, alimony (maintenance) is not tax deductible in Illinois. The Tax Cuts and Jobs Act of 2017 eliminated the federal deduction for maintenance payments in divorce agreements executed after December 31, 2018. Illinois conforms to federal tax treatment, so neither party claims a state tax benefit. Pre-2019 agreements may retain the prior tax treatment.
How long does child support last in Illinois?
Child support in Illinois continues until the child turns 18 years old, or 19 if the child is still attending high school under 750 ILCS 5/505. Courts may order extended support for children with disabilities or educational expenses. Child support ends upon emancipation, the child's marriage, or adoption by another person.
Can I receive both alimony and child support at the same time?
Yes, Illinois courts frequently award both maintenance and child support when a lower-earning spouse has custody of minor children. The obligations are calculated independently using different formulas. Child support is determined first using income shares guidelines, then maintenance is calculated based on net incomes. Receiving one does not reduce eligibility for the other.
What happens to alimony if my ex-spouse remarries?
Maintenance terminates automatically upon the recipient's remarriage under 750 ILCS 5/510. The paying spouse's obligation ends on the date of remarriage without requiring a court order. Maintenance also terminates if the recipient cohabits with another person in a conjugal relationship or upon the death of either party.
How do I modify child support or alimony in Illinois?
Either party can petition for modification by demonstrating a substantial change in circumstances. For child support, a 20% or greater income change typically qualifies. For maintenance, job loss, disability, retirement, or significant changes in either party's financial situation may justify modification. Courts will not modify retroactively except to the date of filing the modification petition.
What is the minimum child support payment in Illinois?
Illinois presumes a minimum child support of $40 per month per child for obligors with gross income at or below 75% of the federal poverty guidelines (approximately $11,400 annually for a single person in 2026). The maximum total obligation for low-income obligors is capped at $120 per month regardless of the number of children.
Does cohabitation affect alimony in Illinois?
Yes, maintenance terminates if the recipient cohabits with another person in a conjugal relationship under 750 ILCS 5/510. The paying spouse must prove that the recipient is in a marriage-like relationship involving shared residence, shared finances, and a romantic or sexual relationship. Courts examine the totality of circumstances when evaluating cohabitation claims.
How does shared custody affect child support in Illinois?
When the non-custodial parent has 146 or more overnights annually (40% parenting time), Illinois applies a shared parenting formula that multiplies the basic support obligation by 1.5 before calculating each parent's share. This adjustment recognizes that both parents incur direct child-rearing expenses when sharing significant parenting time.
Author: Antonio G. Jimenez, Esq. Credentials: Florida Bar No. 21022 | Covering Illinois divorce law
Filing fees current as of January 2026. Verify amounts with your local circuit clerk before filing.