A permanent separation is a separation, normally in preparation for a divorce. For many divorcing couples, a permanent separation is the roll down the runway toward the takeoff of life as a single people. Almost all divorcing couples at some point agree that the marriage will end and that they intend to go their separate ways, legally and forever, and when this happens, the couple separate permanently. At this point, the spouses have abandoned all hope of reconciliation; they intend to divorce.

Even when couples agree to divorce, very often one or both spouses need time to adjust to the new situation. A permanent separation fills this gap. Sometimes couples who separate permanently do nothing more for some time. As divorce lawyers will attest, in most marriages where a couple have made a good faith effort to "make it work," it is a rarity to find two people who decide to divorce at the same time. One spouse calls it quits against the wishes of the other, and the person who is left needs time to catch up. For many, the permanent separation is catch up time. Very often the beginning of a permanent separation is the DOS - the date of separation, a very important date in affixing the responsibility for debts and the value of assets for distribution. Some jurisdictions permit divorcing couples to live together even when divorcing; others require a physical separation - separate residences. In a permanent separation, most couples that can live apart physically do so.

Sometimes, people call a permanent separation "living apart," and in some states such separations may change property rights. For example, most states consider property accumulated and debts incurred during the living apart and divorce to be the separate property or debt of the person who accumulated it.