What do you need to include in your donation acknowledgment letter? A donation acknowledgment letter (sometimes called a donation receipt or thankyou letter) is an email or paper that recognizes a charitable contribution.Below are the donation lines that have been established within Pennsylvania personal income tax law. When acknowledging these donations, include the name of the donor, the number of shares, the name of the security, and the date when the transfer was completed. The person acknowledging the record must personally appear before the notary. Donation acknowledgment letters are more than just a donor tax receipt. There are certain items to include for tax purposes. Within 90 days of the letter from the DCED the business must send proof of the contribution to the DCED. This would be the written acknowledgment from BLOCS.