A gift acknowledgment letter weaves together your nonprofit's appreciation, engagement, and compliance efforts following a donor's generosity. What do you need to include in your donation acknowledgment letter?Gift acknowledgement letters are important for two reasons. First, they provide proof so donors can claim a US tax exemption. A donor acknowledgement letter should include a few specific items to assist the donor and help your organization comply with IRS regulations. Include the nonprofit's EIN so the the donor can to check the charity's tax-exempt status with the IRS. Want to learn how to write and structure donor acknowledgment letters? Check out these tips and sample letters to make a greater impact. First paragraph: Immediately thank donors for their gift. Lee McIntire recalled the final conversation he had with his son, Justin McIntire, just two days before he was killed in the line of duty.