I was using Planned Giving Manager recently to check values in a table of gift annuity deductions. To my surprise, my results differed markedly from the values in the table. Although I noticed that there was a small difference between the IRS discount rate I used (2.2%) and the one used in the table (1.8%), the difference in deductions was so great that I was worried that I had stumbled upon a bug. Not so. It turned out that the small difference in IRS discount rates was the whole story.