The definition of "legal separation" depends on your state of residence. Generally, if you and your spouse stop cohabitation, you will be deemed to be "separated". If you go through the court system and a court order is issued or you have an approved settlement agreement, you will be deemed to be "legally separated".
A trial or informal separation - whether accompanied by an agreement or otherwise - may or may not be a legal separation. All separations - whether legal separations or not under state law -- can be reversed at any time before the Court grants a divorce to either party.
In legal separations, you may or may not enter into a property settlement and support agreement. In some instances, you would finalize everything except the issue of divorce; in other situations, you may not.
In some states, legal separations can be as expensive as divorces, if not more so. Some states require a couple to remain separated for a period of time before divorce. In others, there is a "cooling off" period between the time of filing and when a divorce hearing can be held. The "cooling off" period is based on the state's desire to try to help married people reconcile and keep their relationship together.
In a legal separation, since you are still married, you are not free to remarry. And, depending on where you live, adultery that takes place after the initial separation but before the divorce may cause financial ramifications.
If you are paying support to a spouse, for that support to be tax deductible, there must be an actual separation and some type of agreement setting forth what is to be paid and when as spousal support. Folks who choose the stay in the same house and live in separate bedrooms are generally not "legally separated" and can not deduct support payments made to the other.
Legal Separation is only one part of the divorce process. To learn how to protect yourself in a divorce, you'll need a FlyingSolo membership. A FlyingSolo membership gives you access to all of Jan Warner's comprehensive online divorce resources. New resources are posted free for 30 days, but after that, they are only available to FlyingSolo members. A lifetime membership is only $10.00. Membership is quite affordable when you consider the benefits.