A taxpayer is considering two alternative investments. A Series EE U.S. government savings bond accrues 3.5% interest each year. The bond matures in three years, at which time the principal and interest will be paid. Alternatively, a bank will pay the taxpayer a 3.5% interest rate each year if he agrees to leave money on deposit for three years. What tax advantage does the Series EE bond offer that is not available with the bank deposit?