Offer Letter Mortgage: A non-contingent offer of employment, in letter form, by the employer, which documents the start date, position of the job, salary, benefits, terms, and duties of the employee. The employment offer letter needs to be signed by the mortgage loan applicant and the new employer. This tool is used by college graduates and employees switching jobs to secure a mortgage for a home in lieu of a two-year work history at the company that is hiring them.