Here's everything you need to send a legally compliant offer letter to hire a fulltime employee in Canada. You may get an "offer letter" after interviewing with an employer AFTER you obtain your permanent residency.A job offer letter is a document that a Canadian employer gives you (as a temporary worker). It explains the details of your job. Learn everything about job offer letters for immigration, including eligibility criteria, required documents, and the process. An employment verification letter can help prove income for a green card. Find a sample employment verification letter for immigration here. Only some positions require an exam. These details will be noted in the job description. An SSN will not be issued just for the purpose of enrolling in a college or school.