What do you need to include in your donation acknowledgment letter? A good donor acknowledgment letter is both a transaction record and a donor engagement opportunity.Here's how to write one. A gift acknowledgment letter weaves together your nonprofit's appreciation, engagement, and compliance efforts following a donor's generosity. Have standard donor acknowledgment letters at the ready, and make it easy to fill in the donor and contribution information. A donor acknowledgement letter should include a few specific items to assist the donor and help your organization comply with IRS regulations. Sample Matching Gift Letter For Small Nonprofits. Subject: We think your recent contribution can be DOUBLED. Want to learn how to write and structure donor acknowledgment letters? Check out these tips and sample letters to make a greater impact.