What do you need to include in your donation acknowledgment letter? Donation acknowledgment letters are more than just a donor tax receipt.There are certain items to include for tax purposes. Want to learn how to write and structure donor acknowledgment letters? Check out these tips and sample letters to make a greater impact. Here's what nonprofits need to know. A donation acknowledgment letter (sometimes called a donation receipt or thankyou letter) is an email or paper that recognizes a charitable contribution. Don't let your corporate contributors go unthanked -- be sure to acknowledge donations as they come in with this easy to use form with instructions.