The Letter of employment is the same thing as the job reference letter. It is evidence for the jobs you listed in the Job history.You have to write a formal job offer letter. You will need a full time job opening, a job description, start and end dates, salary details. Learn everything about job offer letters for immigration, including eligibility criteria, required documents, and the process. The nonimmigrant USMCA Professional (TN) visa allows eligible citizens of Canada and Mexico to work in the United States as USMCA professionals. A job offer letter from a Canadian employer is a crucial document for obtaining a work permit and potentially immigrating to Canada. Official Seal of the State of Arizona. Contact. ADOA Human Resources. Complete a background investigation, including a polygraph, to receive an FBI Top Secret Security Clearance.