Treasury bonds (T-bonds) are US government debt securities with a maturity of 10 to 30 years. They pay a fixed interest rate to the purchaser on a semiannual basis until maturity. At maturity, the purchaser is paid the principal (the face value of the bond). Because they are considered to have low credit or default risk, they generally offer lower yields relative to other bonds. The interest is tax-exempt at the state and local levels, but is taxed by the federal government.