Average and Effective Interest Rates

The table below provides two types of interest rates—the average annual special-issue rate and the effective rate.

• The average special-issue interest rate for a calendar year is the average of the 12 monthly interest rates on new issues during the year.
• An effective interest rate for a calendar year is the interest earned in that year divided by the average level of assets held during the year. This rate reflects the entire portfolio of securites held by the Social Security trust funds (OASI and DI). Effective rates for the trust funds on a combined basis are shown below; rates for each trust fund, separately, are also available.