When you and your spouse part ways, certain issues must be addressed whether you actually divorce or not. If you have children, one of you may need to pay child support to help support them. There might also be issues of who is going to make payments toward marital debt and who gets to keep certain property. Filing for separation can cement the terms of your separation into a legal and binding court order. You're still married, but you have the same protection as you would if you had gotten divorced.
Call the family court in your county to find out if your particular state requires you to file a petition for legal separation. Most do. Ask the clerk if the court has printed forms available so you can just fill in the blanks and the details of your specific situation. If the court can't give you a format, many legal websites offer full packets with all the documentation and instructions you'll need to file for a legal separation, tailored to the laws in your state.
Complete your petition. Some states, such as Washington, require that both you and your spouse sign a joint petition for legal separation. If only you sign the petition, you must formally serve your spouse with a copy. Take the original petition and two copies to the courthouse and file it with the clerk. The clerk will keep the original and give you back two stamped copies.
Serve the filed petition on your spouse if she did not already sign a joint petition. Have her sign a notarized acknowledgment that she received it and file this with the court as well.
Prepare a separation agreement, detailing all the terms by which you and your spouse agree to live separate and apart. The agreement should include who is paying for what, a parenting plan if you have children, and details of any financial contributions either of you are planning to make to the other's household. If you're unsure of the format to follow, many legal websites offer forms for download. A sample separation agreement is generally not something your local courthouse can provide you with.
Sign the separation agreement and have your spouse sign it as well. In some states, you may have already received a date for a court hearing when you filed your petition. Other states may require you to call and schedule a hearing once you have the signed separation agreement. In either case, take the separation agreement with you to court. The judge will review it, sign it and incorporate it into your separation decree.