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?Examples include your standard donation request letter, end-of-year donation letter, and fundraising appeal letter. A donor acknowledgement letter should include a few specific items to assist the donor and help your organization comply with IRS regulations. My research on thank you letters culminated in a list of the 20 Characteristics of Great Thank You Letters which was published in DonorCentered Fundraising. Acknowledgement letters should be mailed no later than one week (57 business days) from the date of the gift. What information must the organization include in the written acknowledgement letter? Include the nonprofit's EIN so the the donor can to check the charity's tax-exempt status with the IRS. 1. Cash. This is pretty straightforward—if you receive a donation of liquid money, then you've received a cash gift! First paragraph: Immediately thank donors for their gift.