Some buyers can use an offer letter mortgage to qualify for a home loan before starting their new job. Here's how offer letter loans work.Provide proof of job offer. At a minimum, the letter should show a clear, noncontingent job offer. It needs to outline your salary and start date for the new position. A letter of employment helps mortgage lenders verify your job and current income. Providing this letter is a common requirement when applying for a mortgage. An employment letter is a crucial document you need to secure a home loan. Read about how to write a winning employment letter for mortgage. An offer letter; A letter verifying your title change; Your most recent pay stub; A verification of employment (VOE) from your new employer.