The CPI-U is published monthly by the Department of Labor's Bureau of Labor Statistics. The semiannual inflation rate is then combined with the fixed rate of an I Bond to determine the bond's Earnings Rate for the next six months. Your I Bond will grow at an Earnings Rate we announced in May. Six months later, in April, your I Bond will pick up the Earnings Rate announced in the previous November. Remember, the fixed rate of return, the rate your bond earns over inflation, stays the same.
Bonds fit all budgets.
This makes it easy to keep track of how your bonds grow. Earnings are added to the bond each month, and interest is compounded semiannually. I Bonds increase in value on the first day of the month. An I Bond's issue date is the month and year when the full issue price is received by an I Bond issuing agent. I Bonds earn interest for up to 30 years.