I am writing to provide an explanation for the gap in my employment history as indicated in my mortgage application. Explain what caused the employment gap, and be honest about it.There are lots of reasons why people aren't employed. 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 best to keep your letter of explanation short and sweet. Include as much detail as needed, but address only the specific information the lender requested. 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 applicant must provide an explanation letter for employment gaps in excess of 30 days unless their income history is clearly seasonal in nature.