Legal separation in Illinois keeps you legally married while resolving support and parenting issues, while divorce permanently dissolves the marriage and allows remarriage. Both are filed in the circuit court under the Illinois Marriage and Dissolution of Marriage Act, both require a 90-day residency, and both cost roughly $250-$388 to file. The core difference: only divorce ends the marriage.
Key Facts: Legal Separation vs. Divorce in Illinois
| Factor | Legal Separation | Divorce (Dissolution) |
|---|---|---|
| Filing Fee | $250-$388 (varies by county; Cook County $388) | $250-$388 (varies by county; Cook County $388) |
| Waiting Period | No mandatory wait; 30-day court processing typical | No mandatory wait when spouses agree; 30-day processing typical |
| Residency Requirement | One spouse Illinois resident, filed where either resides | One spouse resident 90 consecutive days before judgment |
| Grounds | Living separate and apart without fault | Irreconcilable differences (no-fault only since 2016) |
| Property Division Type | Court cannot divide property unless both agree | Equitable distribution under 750 ILCS 5/503 |
| Marriage Status After | Still legally married; cannot remarry | Marriage dissolved; both may remarry |
Fees are as of March 2026. Verify with your local clerk before filing.
What Is Legal Separation in Illinois?
Legal separation in Illinois is a court remedy under 750 ILCS 5/402 that allows a spouse living separate and apart to obtain reasonable support and maintenance without ending the marriage. The statute states that any person living separate and apart from a spouse may seek a remedy for reasonable support while living apart. The couple remains legally married, cannot remarry, and the court issues a judgment for legal separation rather than a dissolution.
The action must be brought in the circuit court of the county where the petitioner or respondent resides, or where the parties last resided together as spouses. Commencement, temporary relief, and trial procedures mirror those in dissolution cases, with one major limitation: temporary relief in a separation action is restricted to the categories listed in subdivision (a)(1) and items (ii), (iii), and (iv) of subdivision (a)(2) of 750 ILCS 5/501. A petition must include each spouse's age, occupation, residence, the date of marriage and separation, and whether the couple has minor children. To qualify, the filing spouse must show they live apart and did not cause the separation through their own misconduct.
What Is Divorce in Illinois?
Divorce in Illinois, formally called dissolution of marriage, permanently ends the marriage under 750 ILCS 5/401, restoring both spouses to single status and allowing remarriage. Illinois became a purely no-fault state on January 1, 2016 under Public Act 99-90, eliminating all fault grounds such as adultery, cruelty, and abandonment. The sole ground is now irreconcilable differences that have caused an irretrievable breakdown of the marriage.
To enter a dissolution judgment, at least one spouse must have been an Illinois resident for 90 consecutive days. The 90-day period is measured to the date of judgment, not the filing date, so a couple may file the petition earlier and satisfy the requirement before the case concludes. The statute also provides an irrebuttable presumption of irretrievable breakdown when the parties have lived separate and apart for a continuous period of at least six months immediately before judgment under 750 ILCS 5/401(a-5). Couples who agree may waive this six-month period. Unlike legal separation, a divorce court has full authority to divide all marital property and assign debts under 750 ILCS 5/503.
Legal Separation vs Divorce Illinois: The Core Differences
The central difference between legal separation vs divorce Illinois recognizes is finality: divorce dissolves the marriage and permits remarriage, while legal separation preserves the marital bond. A judgment for legal separation under 750 ILCS 5/402 does not bar either spouse from later filing for divorce, and if that spouse meets the Section 401 requirements, the court shall grant the dissolution.
A second key distinction involves property. In a divorce, the court divides marital property in just proportions under 750 ILCS 5/503 regardless of marital misconduct. In a legal separation, by contrast, the court may not value or allocate property unless both spouses agree to include property division in a separation agreement. This means legal separation cannot force a property split. A third difference concerns maintenance: if a separated spouse later files for divorce, temporary and permanent maintenance are decided de novo, unless a separation agreement set non-modifiable permanent maintenance. Because the difference between separation and divorce affects taxes, insurance, inheritance, and remarriage rights, many couples treat judicial separation as a temporary step rather than a permanent status.
Filing Fees and Court Costs in Illinois
Filing fees for both legal separation and divorce in Illinois range from $250 to $388 depending on the county, with Cook County charging $388.00 for the petitioner. As of March 2026, the petitioner pays the filing fee at the time of e-filing. In an uncontested Cook County divorce, the respondent must also file an Appearance and pay a $251.00 appearance fee, bringing the combined cost to roughly $639.00 when both documents are filed together. DuPage County charges approximately $348 for the petitioner, illustrating county-by-county variation.
Additional costs apply when the respondent does not voluntarily appear. Sheriff service in Cook County costs about $60, while a private process server typically charges $50 to $100. Spouses who cannot afford these costs may apply for a fee waiver under Illinois Supreme Court Rule 298, which generally requires household income at or below 125% of the federal poverty guidelines. These figures are current as of March 2026. Verify with your local circuit clerk before filing, because clerks update fee schedules periodically and amounts differ across all 102 Illinois counties.
Residency Requirements for Both Options
Illinois requires at least one spouse to be a resident of the state for 90 consecutive days before the court enters judgment, under 750 ILCS 5/401(a). Only one spouse must satisfy this 90-day requirement; both parties do not need to live in Illinois. Military personnel stationed in Illinois for 90 or more days also meet the residency provision. The 90-day clock runs to the date of judgment rather than the filing date, allowing a petition to be filed before the period is complete.
Legal separation has a comparable but distinct rule. Under 750 ILCS 5/402, the separation action must be brought in the circuit court of the county where the petitioner or respondent resides, or where the parties last lived together as spouses, and the filing spouse must live in Illinois. There is no separate county-residency duration requirement, but venue rules under 750 ILCS 5/104 control which county is proper. When minor children are involved, a separate jurisdictional consideration applies: the children generally must have lived in Illinois for at least six months to satisfy UCCJEA home-state jurisdiction for parenting decisions.
Why Choose Legal Separation Instead of Divorce?
Couples choose legal separation instead of divorce in Illinois for financial, religious, or personal reasons, because separate maintenance under 750 ILCS 5/402 provides court-ordered support while preserving the marriage. Illinois imposes no time limit on a legal separation, so it can serve as a long-term arrangement or a temporary bridge while spouses decide whether to reconcile or proceed to divorce.
Common motivations include maintaining eligibility for a spouse's health insurance, preserving certain Social Security or pension benefits tied to marriage length, and honoring religious beliefs that discourage divorce. Some couples use separation to reach the 10-year marriage threshold that affects Social Security derivative benefits while living apart. Because the court cannot divide property in a separation absent agreement, spouses who want to keep their financial estate intact while clarifying support obligations may prefer this route. The key trade-off is finality: judicial separation does not allow remarriage and does not automatically resolve property. If circumstances change, either spouse can convert the matter into a dissolution by filing under 750 ILCS 5/401 and meeting the residency and grounds requirements.
Property Division: How the Two Differ
Property division marks the sharpest legal contrast between separation and divorce in Illinois. In a divorce, the court divides marital property in just proportions under 750 ILCS 5/503, applying equitable distribution rather than a strict 50/50 split. Illinois courts weigh 12 statutory factors, including each spouse's contribution, the duration of the marriage, economic circumstances, and tax consequences, and they recognize homemaker contributions as equal to financial ones under 750 ILCS 5/503(d)(1).
In a legal separation, the court has no authority to value or allocate property unless both spouses agree to include property division in a separation agreement. This limitation under 750 ILCS 5/402(b) means separated spouses generally keep title and control of assets as they held them, which can leave significant financial questions unresolved. Marital property in a divorce includes assets and debts acquired after the marriage and before the dissolution judgment, regardless of whose name is on the title. Non-marital property—items owned before marriage, inheritances, and gifts—stays separate unless commingled to the point it cannot be distinguished, in which case it may become marital under 750 ILCS 5/503(c)(1). Retirement accounts are divided through a QDRO, while Illinois government pensions use a QILDRO under 40 ILCS 5/1-119.
Maintenance and Support in Separation and Divorce
Maintenance, Illinois's term for spousal support, is available in both legal separation and divorce under 750 ILCS 5/504, and it is not automatic—courts award it only when one spouse shows financial need and the other has the ability to pay. When the spouses' combined gross annual income is below $500,000 and the payor has no prior support obligations, courts apply the statutory guideline formula: 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.
Duration is tied to marriage length using statutory multipliers under 750 ILCS 5/504(b-1). Marriages of five years or less receive maintenance for 20% of the marriage's duration, 5-10 years at 40%, 10-15 years at 60%, and 15-20 years at 80%. For marriages of 20 years or more, the court may order maintenance for a period equal to the marriage length or for an indefinite term. Illinois recognizes four maintenance types: fixed-term, indefinite, reviewable, and reserved. Importantly, when a legally separated spouse later files for divorce, maintenance is recalculated de novo unless a separation agreement fixed non-modifiable permanent maintenance, so a separation award is not automatically locked in.
How to Convert a Legal Separation to a Divorce
A legally separated spouse in Illinois can convert the matter to a divorce by filing a petition for dissolution under 750 ILCS 5/401, and the prior separation judgment does not bar that action. The statute under 750 ILCS 5/402 expressly states that a proceeding or judgment for legal separation shall not prevent either party from instituting a dissolution action, and the court shall grant the divorce if the moving spouse meets the Section 401 requirements.
The key requirements remain the same: at least one spouse must have been an Illinois resident for 90 consecutive days before judgment, and the marriage must show irreconcilable differences. Because Illinois is no-fault, the prior separation often helps establish the irretrievable breakdown, and a continuous six-month period of living separate and apart creates an irrebuttable presumption of breakdown. When the spouses convert, maintenance is decided de novo unless their separation agreement provided non-modifiable permanent maintenance. Property not divided during the separation is then subject to equitable distribution under 750 ILCS 5/503. The filing fee for the dissolution petition again runs $250 to $388 depending on county, the same range as the original separation filing.