If you had earned that money--i.e. it was pay for work you had done, or commissions for sales you had made, and you should have been paid for it in due course anyway--then the employer may not require you to sign a separation agreement to get it. It may be the case that the agreement is not enforceable, since you were not given consideration for it; that is, to make an agreement like this enforceable, you must be given something to which you are not already entitled in exchange for signing it. Typically, if an employer wants you to sign a separation agreement, they offer you additional compensation--an extra 2, 4, or more weeks pay; to pay for your health insurance for some time after termination; etc.--in exchange for signing. You may wish to consult with an employment attorney to discuss your rights and recourse.