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?In this article, we'll show you exactly how to write a compelling, effective thank-you letter for donations. Here's 20 ideas for how to make your donation thank you letters really make an impact – and hopefully create more lifelong donors. Gift acknowledgement letters are important for two reasons. First, they provide proof so donors can claim a US tax exemption. Include the nonprofit's EIN so the the donor can to check the charity's tax-exempt status with the IRS. First paragraph: Immediately thank donors for their gift. Fundraising for Nonprofit Board Members Don't Miss It! If you provide the charity with a cash gift, there may be some limitations.