Yes, Illinois is a no-fault divorce state. Since January 1, 2016, irreconcilable differences causing an irretrievable breakdown of the marriage has been the only legal ground for divorce in Illinois. You cannot file based on adultery, cruelty, desertion, or any other allegation of wrongdoing, and you do not have to prove your spouse did anything to cause the split.
What Changed in 2016
Before 2016, Illinois law let a spouse file on fault-based grounds including adultery, desertion, habitual drunkenness, and extreme cruelty. Those grounds required the filing spouse to prove specific misconduct and, at the same time, show they had not provoked it. The statute also required a two-year separation before a court could grant a no-fault divorce, though spouses could agree to shorten that to six months.
The 2016 overhaul eliminated all fault grounds and the separation requirement in its old form. The Illinois Marriage and Dissolution of Marriage Act now provides a single basis: irreconcilable differences have caused the marriage to irretrievably break down, past efforts at reconciliation have failed, and future attempts would not serve the family’s best interests.1Illinois General Assembly. Illinois Code 750 ILCS 5/401 – Dissolution of Marriage Neither spouse explains why the marriage ended, and the court does not assign blame.
Who Can File in Illinois
At least one spouse must have been a resident of Illinois, or stationed here as a military member, for a continuous period of at least 90 days immediately before the petition is filed.1Illinois General Assembly. Illinois Code 750 ILCS 5/401 – Dissolution of Marriage There is no separate county residency requirement.
How You Prove Irreconcilable Differences
There are two paths.
The first is the six-month separation route. If you and your spouse have lived separate and apart for a continuous period of at least six months before the judgment is entered, the law treats the irreconcilable-differences requirement as conclusively met. The court cannot second-guess it. Illinois courts have also recognized that “separate and apart” does not require separate addresses; spouses can live separately under one roof by keeping separate bedrooms and no longer functioning as a married couple.
The second path is available when you have not been separated that long. The court makes its own finding that irreconcilable differences exist based on the evidence in front of it. In practice this is straightforward when both spouses agree the marriage is over, and it remains available even when one spouse resists. Most divorces move forward without waiting out the six months because the parties cooperate on the finding.
Can My Spouse’s Misconduct Still Matter?
Fault is gone as a ground for divorce, but that does not mean bad behavior is invisible in every part of the case. It depends on what is being decided.
Dividing Property
Illinois divides marital property in “just proportions,” meaning fairly, not necessarily 50/50. The statute directs judges to divide property “without regard to marital misconduct.”2Illinois General Assembly. Illinois Code 750 ILCS 5/503 – Disposition of Property and Debts An affair by itself will not shrink your spouse’s share of the estate.
The narrow exception is dissipation: one spouse spending marital funds on something unrelated to the marriage, for their own benefit, after the relationship has already begun breaking down. Gifts for a new partner or gambling away savings are the classic examples. If a court finds dissipation, it can charge that spending against the dissipating spouse’s share.
Dissipation claims come with hard deadlines. You must file a formal notice at least 60 days before trial, or 30 days after discovery closes, identifying when the marriage began breaking down, what property was dissipated, and when the spending occurred. The claim also cannot reach back more than five years before the divorce petition was filed, or more than three years after you knew or should have known about the spending.2Illinois General Assembly. Illinois Code 750 ILCS 5/503 – Disposition of Property and Debts Miss those deadlines and the claim is gone.
Spousal Maintenance
Maintenance (what most people call alimony) is decided without any consideration of marital misconduct. The statute says so directly.3Illinois General Assembly. Illinois Code 750 ILCS 5/504 – Maintenance It does not matter who caused the marriage to fail. The court weighs each spouse’s income and earning capacity, their contributions to the household, the length of the marriage, and whether one spouse gave up career opportunities for the family.
When combined gross income is under $500,000, Illinois applies a formula: 33.33% of the paying spouse’s net income minus 25% of the receiving spouse’s net income, capped so the receiving spouse’s income plus maintenance does not exceed 40% of the couple’s combined net income.3Illinois General Assembly. Illinois Code 750 ILCS 5/504 – Maintenance Duration is tied to the length of the marriage, with short marriages producing short awards and marriages of 20 years or more possibly resulting in maintenance for the full length of the marriage or indefinitely.
Parental Responsibilities and Parenting Time
Illinois no longer uses “custody” and “visitation.” The terms now are “allocation of parental responsibilities” and “parenting time,” and both are decided under the best interest of the child standard. The court looks at factors like how much time each parent has been caring for the child, the child’s adjustment and relationships, and each parent’s willingness to support the child’s relationship with the other parent.4Illinois General Assembly. Illinois Code 750 ILCS 5/602.7 – Allocation of Parental Responsibilities Parenting Time
A parent’s personal misconduct enters the picture only when it affects the child. The statute says the court “shall not consider conduct of a parent that does not affect that parent’s relationship to the child.”5FindLaw. Illinois Code 750 ILCS 5/602.5 – Allocation of Parental Responsibilities Decision-Making A discreet affair the child never knew about will not weigh in. Substance abuse, domestic violence, exposing a child to dangerous situations, and living with a convicted sex offender are all specifically listed as factors the court takes seriously.4Illinois General Assembly. Illinois Code 750 ILCS 5/602.7 – Allocation of Parental Responsibilities Parenting Time The focus is the child’s safety, not punishing a parent.
The Bottom Line
If you are looking for a way to punish a spouse through the divorce filing itself, Illinois does not offer one. Fault grounds are gone, and the two areas most people expect misconduct to influence, property division and maintenance, are decided without regard to who caused the breakup. The narrow places where conduct still matters are dissipation of marital funds and parenting decisions where a parent’s behavior directly affects the child. Everything else turns on the finances, the length of the marriage, and the child’s best interests.