Find information on government bonds yields, bond spreads, and interest rates. Skip to content. Markets Rates & Bonds. Before it's here, it's on the Bloomberg Terminal. Learn More When does my bond change rates? What have rates been in the past? What is the current composite rate for my I bond? Where can I find more information on rates? What interest will I get if I buy an I bond now? The composite rate for I bonds issued from November 1, 2019 through April 30, 2020, is 2.22 percent. This rate applies for the first six months you own the bond. As a result, there are no 20-year rates available for the time period January 1, 1987 through September 30, 1993. Treasury Yield Curve Rates: These rates are commonly referred to as "Constant Maturity Treasury" rates, or CMTs. Yields are interpolated by the Treasury from the daily yield curve.