The IRS taxes gifts made over a certain dollar amount. A gift letter is a piece of legal, written correspondence explicitly stating that money received isn't expected to be repaid.One, a gift is not taxable for the donor or donee unless it exceeds lifetime gift tax exclusion during their lifetime. Sales of tangible personal property are subject to New York sales tax unless they are specifically exempt. Sales of services are generally exempt. A gift letter is a note from a donor to your lender regarding cash funds for your mortgage 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. Please fill in the blanks below. Gift or Generation-Skipping Transfer (GST) Tax—Complete this part if you expect to owe either tax. Caution: Do not include income tax on lines 5a and 5b.