An incomplete application packet may disqualify an applicant. List experience that relates to the qualifications as required on the job announcement.Finally, review your application before submission to ensure all sections are complete. Contra Costa County only accepts online applications. When viewing a job posting for a currently open examination, you can select the option that says 'Apply'. Click on the application link below. Denotes a required field. What is the Close Date on a job posting? How do I complete an online application? Assignment Date: Contra Costa County Probation Department Volunteer Application Form.