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 mortgage gift letter is a statement that assures your lender the money that came into your account is a gift and not a loan. A gift letter is a letter stating that money you receive from a friend or family member is in fact a gift, not a loan. A gift letter should include the name and contact information of the donor and a statement that no repayment is expected. Use these stepbystep instructions for accepting a cash downpayment gift on a home, including a readytouse mortgage gift letter template.