A counter offer letter is a physical letter or email candidates send to an employer when they want to negotiate the terms of a job offer given to them. The first thing you should put on your job acceptance letter is the date.Include it underneath the header close to the top of your letter. Employment Offer Letter Instructions. A sample letter offering a job contingent upon the results of a background check or other criteria. This letter serves as an offer of employment to you for the University Support Personnel System position. Date Offer Must Be Accepted By – Date finalist is expected to respond, allow a minimum of three business days for acceptance. In the formal offer letter, provide comprehensive details about the position, compensation, benefits, and other pertinent terms.