I am writing to provide an explanation for the gap in my employment history as indicated in my mortgage application. I would suggest a few things to say in the letter.Explain what caused the employment gap, and be honest about it. Mortgage lenders might request a letter of explanation for various red flags that come up in underwriting. Learn how to write one, and download a template. It's really that simple: To Whom It May Concern: The reason I do not have a full time work history is because I was in school, which was a conflict with school. A letter of explanation consists of short descriptions you can use to fill in the gaps in your paperwork for your underwriter.