The 2015 Overhaul That Rewrote Illinois Divorce Law
In July 2015, Illinois passed Public Act 99-90, the most sweeping rewrite of the Illinois Marriage and Dissolution of Marriage Act in a generation. It took effect on January 1, 2016, and it changed how divorce works in this state from the ground up. Nearly a decade later, these rules still define every Illinois divorce, including how courts treat separation.
1. Fault Grounds Disappeared
Before the overhaul, Illinois still recognized grounds like adultery, cruelty, and desertion. The new law eliminated all of them. Today there is exactly one basis for divorce in Illinois: irreconcilable differences. Nobody has to prove wrongdoing, and marital misconduct is not supposed to influence how property is divided.
2. The New Separation Standard: Six Months
This is the change that matters most for timing. Under 750 ILCS 5/401(a-5), if spouses live separate and apart for a continuous period of six months, the law creates an irrebuttable presumption that irreconcilable differences exist. Put simply: after six months of separation, the ground for divorce cannot be contested.
Two details make Illinois unusual and practical here:
- Separate and apart does not require separate homes. Illinois courts have long recognized that spouses can live separate lives under the same roof, which matters for families who cannot afford two households during a case.
- The six months can run while the case is pending. You do not need to wait half a year before filing.
3. "Custody" Left the Vocabulary
The 2016 rules replaced custody with two sharper concepts: allocation of parental responsibilities (who makes significant decisions about education, health, religion, and activities) and parenting time (the schedule). Parents now file parenting plans, and courts allocate responsibilities based on the child's best interests rather than handing one parent a winner-take-all label.
4. Maintenance Became a Formula
Spousal maintenance (what many people still call alimony) moved to statewide guidelines under 750 ILCS 5/504. For most families, the amount is 33.3 percent of the payer's net income minus 25 percent of the recipient's net income, with a cap so the recipient's total does not exceed 40 percent of the couple's combined net income. Duration scales with the length of the marriage.
What About Property and the Date of Separation?
Here is a distinction that trips people up. In some states, property you acquire after a formal date of separation is automatically yours. Illinois is stricter: under 750 ILCS 5/503, property acquired up until the judgment of dissolution is generally presumed marital, no matter when you separated. The six month standard controls the ground for divorce, not the property cutoff. That makes early legal advice valuable if you are separated but not yet divorced and still accumulating income or assets.
The Bottom Line
The 2015 overhaul made Illinois divorce less about blame and more about process: one no-fault ground, a clean six month separation presumption, modern parenting language, and predictable support math. If you are separated, or considering it, and want to understand exactly where you stand, Inspired Law Group can walk you through it. Call (815) 838-5297.
Questions People Ask
What grounds does Illinois use for divorce today?
Just one. Public Act 99-90, effective January 1, 2016, eliminated older fault grounds like adultery, cruelty, and desertion. Today the only basis for divorce in Illinois is irreconcilable differences, and nobody has to prove wrongdoing since marital misconduct is not supposed to influence how property is divided.
Do I have to live in a separate home to meet Illinois's separation requirement?
No. Under 750 ILCS 5/401(a-5), if spouses live separate and apart for a continuous six months, the law creates an irrebuttable presumption that irreconcilable differences exist, and after that point the ground for divorce cannot be contested. Illinois courts have long recognized that spouses can live separate lives under the same roof, which matters for families who cannot afford two households, and the six months can run while the case is pending.
How is spousal maintenance calculated in Illinois?
Spousal maintenance moved to statewide guidelines under 750 ILCS 5/504 as part of the 2016 overhaul. For most families, the amount is 33.3 percent of the payer's net income minus 25 percent of the recipient's net income, with a cap so the recipient's total does not exceed 40 percent of the couple's combined net income. Duration scales with the length of the marriage.
