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. Sample of a Gift Letter.Used when getting a new mortgage and getting a gift from family. A gift letter for a mortgage is proof to the lender that money you've been given for your home purchase is a gift, not a loan to be repaid. The goal of a gift letter is to provide the lender with proof of where the funds came from. To use gift funds, you must provide a gift letter proving the money is not a loan. A gift letter for a mortgage shows your lender that you don't need to repay gift money toward your down payment.