Illinois stands out among equitable distribution states for one reason most people don't expect: it uses a statutory formula for spousal maintenance. Rather than leaving the amount entirely to judicial discretion, Illinois law provides a specific calculation — which makes financial planning more predictable than in many other states. Property division and child support also follow structured frameworks under the Illinois Marriage and Dissolution of Marriage Act (IMDMA). If you're going through a divorce in Illinois, understanding how these systems generally work gives you a clearer starting point.
This page covers how Illinois generally handles property division, spousal maintenance, child support, and retirement accounts. For deeper reading on any topic, the links throughout lead to full guides.
- Illinois's equitable distribution system and the 12 factors courts weigh
- The statutory maintenance formula — how it works and when it applies
- Child support under the Income Shares Model, updated annually
- What happens to retirement accounts — including the Illinois-specific QILDRO for state pensions
- A free calculator to estimate your numbers
Property Division: Equitable Distribution in "Just Proportions"
Illinois follows equitable distribution under 750 ILCS 5/503, dividing marital property in what the statute calls "just proportions" — fair, but not necessarily equal. A 50/50 split is neither presumed nor required. Courts weigh 12 statutory factors to determine what division is appropriate for the specific marriage.
Marital property includes all assets and debts acquired by either spouse after the marriage date and before the final divorce judgment, regardless of whose name appears on the title. Non-marital property — assets owned before the marriage, gifts, and most inheritances — is generally excluded from division and stays with the spouse who owns it. However, commingling non-marital funds with marital accounts can convert them to marital property over time, which is a common source of disputes.
Among the 12 factors Illinois courts consider: the duration of the marriage, each spouse's contributions (including homemaking and child-rearing), each spouse's economic circumstances, the value of non-marital property, tax consequences, and whether either spouse dissipated marital assets. Illinois law explicitly recognizes homemaker contributions as equal in weight to financial contributions — a meaningful protection for spouses who stepped back from careers during the marriage.
Suppose a couple married for 18 years has $500,000 in marital assets. One spouse worked full-time throughout the marriage while the other primarily managed the household and raised children. Applying Illinois's 12 factors — particularly the recognition of homemaker contributions — a court might divide the estate at 55/45 or even closer to equal, reflecting the non-financial contributions made over nearly two decades. A shorter marriage with both spouses earning similar incomes might produce a split much closer to equal. Outcomes depend heavily on the specific facts presented.
For more on how the family home is typically handled in equitable distribution states, see What Happens to the House in a Divorce? and What is Equitable Distribution?
Spousal Maintenance: A Statutory Formula with Duration Tied to Marriage Length
Illinois calls spousal support "maintenance" — and unlike most equitable distribution states, it provides a specific formula for calculating the amount. Under 750 ILCS 5/504, when combined gross income is below $500,000 per year, courts generally apply the following calculation:
When combined gross income exceeds $500,000, the formula does not automatically apply — courts use their discretion and weigh multiple statutory factors to determine an appropriate amount. The formula is also a starting point, not a ceiling: judges retain discretion to deviate based on the 12 maintenance factors in the statute, including each spouse's health, standard of living during the marriage, and earning capacity.
Duration is directly tied to the length of the marriage under 750 ILCS 5/504(b-1)(1)(B). The statute provides multipliers applied to the marriage length:
| Marriage Length | Duration Multiplier | Example: 12-Year Marriage |
|---|---|---|
| Under 5 years | 0.20 × marriage length | — |
| 5–6 years | 0.24 × marriage length | — |
| 10–11 years | 0.52 × marriage length | — |
| 12–13 years | 0.60 × marriage length | ~7.2 years |
| 15–16 years | 0.72 × marriage length | — |
| 20+ years | Court discretion — indefinite maintenance possible | — |
For marriages of 20 years or more, Illinois courts may award indefinite maintenance — meaning support with no fixed end date, subject to modification if circumstances change significantly. Maintenance generally terminates upon the receiving spouse's remarriage or cohabitation with a new partner.
For a broader look at how alimony duration works across states, see How Long Do I Have to Pay Alimony?
Child Support: Income Shares Model with Annual Updates
Illinois uses the Income Shares Model for child support under 750 ILCS 5/505, adopted in July 2017. The model combines both parents' net incomes and matches that figure to the Schedule of Basic Child Support Obligations — a chart that sets a base monthly support amount depending on combined income and the number of children. Each parent then pays their proportional share based on their percentage of the combined income.
One important Illinois-specific detail: the guidelines schedule is updated annually. The most recent update took effect March 2025, reflecting current cost-of-living data. Courts apply the current schedule at the time of the order, and existing orders are not automatically updated — a modification petition is required to apply a new schedule to an existing order.
Suppose Parent A has a net monthly income of $5,500 and Parent B has $2,500, for a combined net income of $8,000. For two children, the Schedule might set a basic obligation of approximately $1,800 per month. Parent A earns roughly 69% of the combined income, so Parent A's share is approximately $1,242 per month. Parent B's share is approximately $558 per month — typically offset against the support they receive as the primary residential parent.
Additional costs for childcare and health insurance are calculated separately and also split proportionally between parents.
Illinois also has a specific threshold for shared parenting adjustments. When a parent has 146 or more overnights per year (approximately 40% of the time), a modified formula applies that accounts for the duplicated household costs of shared care. This threshold differs from Florida's 73-overnight rule and is worth understanding if parenting time is being negotiated.
For a full breakdown of how the Income Shares Model works and how long child support typically lasts, see How is Child Support Calculated? and How Long Do I Have to Pay Child Support?
Retirement Accounts: QDROs for Private Plans, QILDROs for State Pensions
Retirement benefits earned during the marriage are marital property in Illinois, subject to equitable distribution. Both vested and non-vested pension benefits are considered marital property under 750 ILCS 5/503(b) — meaning even a pension the employee spouse hasn't yet qualified to collect may be divided.
Dividing private-sector employer plans — 401(k)s, 403(b)s, and pensions — requires a Qualified Domestic Relations Order, or QDRO. This is a separate court order that instructs the plan administrator to transfer the awarded portion to the receiving spouse without triggering early withdrawal penalties or taxes.
IRAs are handled separately through a transfer incident to divorce, which does not require a QDRO or QILDRO but does require specific language in the divorce judgment and coordination with the financial institution. As with other states, each account requires its own separate order or transfer — couples with multiple retirement accounts need to address each one individually in the settlement.
For a plain English explanation of how QDROs work and what happens to retirement accounts in divorce, see What is a QDRO? and What Happens to My 401k in a Divorce?
See how your Illinois finances might divide.
Enter your income, marriage length, and assets. Get plain English estimates for spousal support, child support, home equity, and retirement splits — in under two minutes. Free, no login required.
Use the free calculator →