A gift letter must contain the donor's name, the gift's value, confirmation that the gift is not to be repaid, and the donor's signature. What Is Needed for a Gift Letter?A mortgage gift letter is a document that helps satisfy the requirement that a borrower's down payment funds come from legitimate sources. The goal of a gift letter is to provide the lender with proof of where the funds came from. 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. In order to be exempt from the sales and use tax, you must meet the requirements of the law and complete the affidavit above. Here's a sample gift letter you can use to prove that the money is truly meant as an outright gift, with no expectation of repayment.