Illinois recognizes one ground for divorce: irreconcilable differences. You do not have to prove your spouse cheated, abandoned you, drank too much, or did anything wrong. If one spouse believes the marriage is permanently broken, that is enough. The state eliminated every fault-based ground in 2016, so the grounds for divorce in Illinois are now purely no-fault. What actually trips people up is not proving grounds — it’s the separation presumption, the residency threshold, and the fact that misconduct still quietly shapes some financial decisions even though it cannot block or expand the divorce itself.
Irreconcilable Differences Is the Only Ground
To grant a divorce, an Illinois court must find that irreconcilable differences have caused the irretrievable breakdown of the marriage, and that past reconciliation efforts have failed or future efforts would be pointless and not in the family’s best interests.1Illinois General Assembly. Illinois Code 750 ILCS 5/401 – Dissolution of Marriage In plain terms, the judge needs to see that the relationship is over and that trying to fix it would be futile.
You do not need your spouse’s agreement. If you testify that the marriage has broken down beyond repair and that reconciliation has gone nowhere, the court can accept that and move forward. Your spouse can appear and argue the marriage is salvageable, but courts almost never deny a divorce when one party genuinely wants out. The statute exists to confirm the marriage is over, not to force anyone to stay in it.
The Six-Month Separation Presumption
The six-month separation period is not a waiting period you have to complete before filing. It creates what the law calls an irrebuttable presumption. If you and your spouse have lived separate and apart for at least six continuous months before the judge signs the final judgment, the court must accept that irreconcilable differences exist. No further proof needed, and nobody can argue otherwise once that clock has run.1Illinois General Assembly. Illinois Code 750 ILCS 5/401 – Dissolution of Marriage
Without the six months, you can still get divorced. The court just evaluates the evidence more directly, looking at whether reconciliation attempts have failed or whether future attempts would serve no purpose. Most contested cases naturally exceed six months of separation by the time they reach a final hearing anyway, so the presumption tends to kick in on its own.
Living Separate Under the Same Roof
You can satisfy the separation requirement while still sharing a home. Financial reality and parenting logistics often make it impossible for one spouse to move out right away, and the law accounts for that. Courts look for evidence that you have stopped functioning as a married couple: sleeping in separate rooms, keeping finances apart, no longer attending events together as a couple. You do not need to maintain two households to prove your marriage is over.
Why the Separation Date Matters Beyond Grounds
The date you separated carries weight past proving irreconcilable differences. It can affect when the marital estate gets valued for division. Assets acquired or debts incurred after separation may be treated differently, and a spouse who burns through money after the relationship is clearly over faces potential dissipation claims. Establishing a clear separation date, even informally, protects you in ways that are not obvious at the start of the process.
Residency: The 90-Day Requirement
Before an Illinois court can dissolve your marriage, at least one spouse must have lived in the state for 90 consecutive days immediately before filing the case.1Illinois General Assembly. Illinois Code 750 ILCS 5/401 – Dissolution of Marriage If neither of you meets that threshold, the court has no jurisdiction and will dismiss the petition. The statute does not require a specific list of documents; residency is established through your testimony and any supporting evidence the court finds persuasive.
Military members stationed in Illinois have an equivalent path. If a servicemember has been posted at an Illinois installation for 90 days before filing, the state courts can handle the divorce regardless of where the servicemember claims legal residence.1Illinois General Assembly. Illinois Code 750 ILCS 5/401 – Dissolution of Marriage
When an Active-Duty Spouse Can Pause the Case
If your spouse is on active duty, federal law lets them pause the proceedings. Under the Servicemembers Civil Relief Act, the court must grant a stay of at least 90 days when the servicemember shows that military duties prevent them from appearing and their commanding officer confirms leave is not available.2Office of the Law Revision Counsel. 50 USC 3932 – Stay of Proceedings When Servicemember Has Notice The protection extends up to 90 days after military service ends. If the court denies a request for an additional stay, it must appoint an attorney for the absent servicemember. Filing the request does not count as appearing in the case, so the servicemember does not waive any defenses by asking for more time.
What Happened to the Old Fault Grounds
Before 2016, Illinois required petitioners to prove specific misconduct: adultery, desertion for a year, habitual drunkenness, extreme cruelty, a felony conviction, or one of several other fault categories. Petitioners could also claim irreconcilable differences, but only after showing a two-year separation, reducible to six months only if both sides agreed in writing. That system turned courtrooms into arenas where spouses publicly attacked each other’s character just to unlock the right to divorce.
The 2016 amendment swept all of that away. Irreconcilable differences became the only ground, the mandatory two-year separation disappeared, and the six-month presumption replaced the old waiver mechanism. A judge no longer hears testimony about who cheated or who drank too much when deciding whether to grant the divorce itself.
Where Misconduct Still Matters
Getting divorced no longer requires proving fault, but people often assume that means bad behavior is irrelevant to the financial outcome. That is only partly true.
The statute is explicit: Illinois courts divide marital property “without regard to marital misconduct.”3Illinois General Assembly. Illinois Code 750 ILCS 5/503 – Disposition of Property and Debts The same rule governs maintenance: a court awards spousal support “without regard to marital misconduct.”4Illinois General Assembly. Illinois Code 750 ILCS 5/504 – Maintenance An affair, by itself, will not increase your share of the assets or guarantee you alimony.
The Dissipation Exception
The one place misconduct bites hard is dissipation of marital assets. If your spouse spent marital money on something that had nothing to do with the marriage, such as funding an affair, gambling sprees, or lavish gifts to a new partner, the court can treat that spending as the wasteful spouse’s share of the property.3Illinois General Assembly. Illinois Code 750 ILCS 5/503 – Disposition of Property and Debts
To raise a dissipation claim, you must file a notice at least 60 days before trial identifying the property dissipated, the time period of the wasteful spending, and when the marriage started breaking down. The claim is limited to spending within three years of when you knew or should have known about it, and in no case earlier than five years before the divorce petition was filed. Dissipation is the sharpest tool available when one spouse has been reckless with shared money, but it requires specifics. You cannot just say they spent too much. You need amounts, dates, and a connection between the spending and the breakdown of the marriage.