Legal separation is not typically defined by the amount of time you and your spouse live apart. In many cases, it depends on whether an agreement or a court order is in place that governs the terms of your separation. State laws vary, and you may be legally separated when an agreement or court order exists, even if neither of you has moved out of the marital home yet.
Some states, such as New York, do not provide for a litigated separation process. In these jurisdictions, you and your spouse are separated when you create an agreement resolving all pertinent issues and you sign it. The agreement acts as an enforceable contract, and it paves the way for one of you to leave the marital home.
Separation by Court Order
Depending on where you live, you may have the option of filing a petition for legal separation, just as you would for divorce. The complaint may require that you cite grounds for the separation. If your state requires that you have been living apart for a period of time, you would have to meet this requirement before you can file for a legal separation.
Separation as Grounds for Divorce
If you're using your separation as grounds for divorce, you and your spouse may have to live separately, in different households, to qualify. For example, in North Carolina, the only grounds for absolute divorce are separation for one year or incurable insanity. The separation period begins when you move into separate households. Other states, like Virginia, recognize that you can legally live separately and apart while under the same roof.