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 short letter like this sample gift letter will cover all of the requirements your lender needs.A gift letter for a mortgage shows your lender that you don't need to repay gift money toward your down payment. A mortgage gift letter is a document that helps satisfy the requirement that a borrower's down payment funds come from legitimate sources. The District commingles cash receipts from the U.S. Department of Agriculture with similar State grants.