I am writing to provide an explanation for the gap in my employment history as indicated in my mortgage application. 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. Explain what caused the employment gap, and be honest about it. There are lots of reasons why people aren't employed. A letter of explanation consists of short descriptions you can use to fill in the gaps in your paperwork for your underwriter. A letter of explanation can clarify your financial situation and get you one step closer to qualifying for a mortgage. The lender did not obtain an adequate explanation for the employment gap from August 2002 to March 2003 from the co-borrower. Show All Answers. 1. He resigned from the U.S. Army in 1856 to become a sugar plantation owner in Louisiana.