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. Only certain gifts can be used for your down payment.Gifts can only come from family members or friends who have a close relationship with you. A gift letter for a mortgage shows your lender that you don't need to repay gift money toward your down payment. 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.