Generally a job offer letter will show your new salary and that will help that you will be financially able to pay rent. And if they refuse at first, they will often accept if you offer to pay the first few months of rent in advance.You can also use an official offer letter as proof of income as long as it includes your salary. Learn how to write a proof of income letter with our stepbystep guide and use our fillintheblanks template as an example. 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. A sample letter offering a job contingent upon the results of a background check or other criteria. 728 Likes, 239 Comments. According to MassLandlords. Net, an offer letter is a common method of verifying income.