This guide explains how to document gift funds for a mortgage and meet lender requirements. A gift letter is a document certifying that your family member is giving you money to cover all or a portion of your down payment or closing costs.The letter must explain who is gifting the money, where the donor's funds are coming from and the relationship between the donor and the recipient. A mortgage gift letter is a document that helps satisfy the requirement that a borrower's down payment funds come from legitimate sources. Edit your gift letter for mortgage online. Type text, add images, blackout confidential details, add comments, highlights and more. Series of images with parents and children filling out paper and online forms. Child care can be costly. 800-252-8980 (toll free in Illinois). Close-up of gift details on form.