Donation acknowledgment letters are more than just a donor tax receipt. There are certain items to include for tax purposes.What do you need to include in your donation acknowledgment letter? The certificate of acknowledgment (PDF) must be in the form set forth in California Civil Code section 1189. There are many other reasons to send a receipt after receiving a donation. This step-by-step guide will help you fill out the donation tax receipt and get things in order for tax season. What is required in a donation acknowledgement letter? WITNESS my hand and official seal. Signature. (Seal). A notary public or other officer completing this certificate verifies only the identity of the individual. 8283 acknowledging receipt of the donated item.