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 gift letter for a mortgage shows your lender that you don't need to repay gift money toward your down payment.A gift letter is an important, formal, legal piece of documentation that can help explain that a (usually rather large) sum of money was gifted to you. A signed gift letter from her parents. A mortgage gift letter is a document that helps satisfy the requirement that a borrower's down payment funds come from legitimate sources. A gift letter is a note from a donor to your lender regarding cash funds for your mortgage down payment. Generally if the funds are in the account for more than 90 days before closing you do not need a gift letter. 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. A gift letter is a piece of legal, written correspondence explicitly stating that money received from a friend or relative is a gift. A gift letter is a written explanation provided to your mortgage lender when someone else gives you money toward a home purchase.