In Illinois there is a two year waiting period for living separate and apart for irreconcilable differences, but that may be reduced to six months if both of you agree to it and file a waiver and stipulation waiving the two year period. 750 ILCS 5/401.
Illinois does not require the parties to live separate for any period of time prior to filing for divorce. However, if you wish to file using grounds of irreconcilable differences there is a requirement that the parties live apart - not as husband and wife, even if in the same household - for a period of 2 years if the parties do not stipulate (agree) to irreconcilable differences, or 6 months if they do stipulate.
You do not have to be separated any particular length of time, before filing a divorce case in Illinois. However, in order for the court to enter a final judgment, there must be proper grounds for the divorce -- and that is when the length of separation could matter. Illinois has both "fault grounds," such as repeated mental cruelty, repeated physical cruelty or abandonment for over a year -- and "no- fault" grounds, called "irreconcilable differences."
The length of separation does not matter at all if the judgment is entered based on a "fault ground," and many people will use "mental cruelty," as the easiest fault ground to prove (usually just through testimony, without any documents or other evidence). However, if you would like to use "no-fault grounds," (irreconcilable differences) the husband and wife must have been living "separate and apart" for two years at the time of the judgment, OR they must have been living "separate and apart" for six months, and then agree (in writing) to waive the remainder of the two-year separation period.
Please note: The phrase "separate and apart" does not mean living at separate addresses. Illinois courts have decided that a couple who shares the same house can be living "separate and apart," as long as they are living separate lives. This usually means not sharing bank accounts, not sharing a bedroom, not having sexual relations, not going out together socially, and not really communicating effectively.
A weekly guide with tips and legal advice for each stage of the process.