In some states, grounds for divorce are pretty straightforward – you have irreconcilable differences, and that's that. Illinois recognizes irreconcilable differences as a ground, but that's where the simplicity ends. A six-month rule applies in this state, although there's no waiting period if you file on fault grounds.
Irreconcilable differences is the only no-fault ground in Illinois, and it requires a two-year waiting period. However, you don't necessarily have to wait out the whole two years before getting your divorce. If you and your spouse agree that your marriage can't be saved, you can jointly sign a waiver of the two-year rule and submit it to the court. This reduces the waiting period to six months. The six-month period does not have to occur before you file for divorce, but your divorce won't be granted until you and your spouse have lived separately for the required period of time. If your spouse resists signing the waiver, then changes her mind and agrees, you can submit it to the court at any time. If you've already lived apart for six months or more, you can be divorced immediately.
Separating Under One Roof
Illinois law concedes that you and your spouse can be separated while still living in the same home. However, the court may require some evidence that your marriage has broken down and that you're not residing together as husband and wife such as separate bank accounts.