A separation agreement is a legally binding agreement that is willingly entered into by both spouses when they agree to the terms of their separation. Agreement with regards to ownership of property and assets, financial assistance, child support, child custody, and visitation are all matters that are included in a typical separation agreement. To make the agreement legally binding, it is written down and the lawyer for one of the spouses will take it to the judge to be signed. If it is not signed by the judge it is not considered a binding agreement.
Justipedia explains Separation Agreement
When both parties to a divorce agree to all the terms that affect them, a separation agreement is a common method of saving time and expense through a traditional divorce trial.