Illinois recognizes legal separation for a married couple that would like to resolve issues involving their marital relationship without terminating the marriage. For example, in a legal separation an Illinois court will decide how your marital property should be divided and all child support issues. To apply for legal separation in Illinois, contact the circuit court clerk in your county to obtain the form for legal separation. Complete the necessary paperwork. You will need to include information on the form about both you and your spouse. For example, the form will ask you to provide basic information including your financial situation and whether you have any children. Next, you will need to sign the form before submitting it to the court. If both you and your spouse agree to the legal separation, you both must sign the form. Finally, pay the legal separation filing fee. The fee to file for legal separation is different in each county, so contact your circuit court clerk to determine the relevant filing fees.