Step 1: Prepare and file the following forms (you will need to provide the original and at least one photocopy of each form). The application for letters of administration is Form DE150 submitted with the petition and order for probate at the time the petition is filed with the court.No, a lawyer is not required. The mission of the Clerk-Recorder's Office is to secure, preserve, and make accessible the County's vital, business, and official records. The completed form DE150 should then be submitted to the probate court in the county in which the deceased resided in at the time of death. This petition must be filed with the California Superior Court in the County where the deceased resided at the time of their death. Navigate the estate administration process with Law Offices of Timothy D. Henry. Contact us for compassionate assistance today. In this video, we're going over two forms, DE 140 which is the Order for Probate, and DE 150 which are the Letters, Testamentary, or Letters of Administration. Instead, think of a Will as a kind of letter written to a probate judge, expressing the desires of the deceased.