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. Hi, I'm new to this but need advice.My parents have given me and my brother a substantial cash gift. Download a gift affidavit form in PDF or Word format to attest to and record the gratuitous and voluntary transfer of a gift. 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 an important, formal, legal piece of documentation that can help explain that a (usually rather large) sum of money was gifted to you. 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.