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.A short letter like this sample gift letter will cover all of the requirements your lender needs. If you use gifted funds toward your home purchase, your mortgage lender will need a gift letter to explain that the money is not a loan. A mortgage gift letter states that you received money as a genuine gift to use toward a down payment, rather than a loan. A mortgage gift letter is a simple but essential document that assures lenders the funds you received are a gift, with no repayment expected. Use these stepbystep instructions for accepting a cash downpayment gift on a home, including a readytouse mortgage gift letter template.