Your signature and date are considered an acceptance of employment and acknowledgement that you have reviewed the Benefits Summary. Do I consent to electronic service when I efile?Need help drafting a job offer letter? You may complete an on-line application at the Contra Costa Human Resources Department at 651 Pine St., 2nd Floor, Martinez, CA 94553. Please fill out and print form, and attach supporting documentation. An offer letter is a document that holds the terms of employment for a new hire. It includes the salary, benefits, and other important information.