The date of separation is important, because that is the date on which the “Marital Estate” is identified. In other words, it is the date that determines the assets and liabilities that will be relevant in divorce.
The law says that the date of separation is the date on which spouses begin living separate and apart. Separate and apart is defined as “the cessation of cohabitation.” So, if a spouse moves out of the house and rents an apartment, the lease can prove the date of separation.
Some couples live separate and apart in the same household. There are many ways to prove living separate and apart, but if you are unable to do so, or if it does not matter (think winning a lottery ticket the day after the date of separation and how important that date can be), the law says that the date on which a Complaint in Divorce is filed with the Court is the date of separation.