Like this: Let's say you buy your I Bond in October. Your I Bond will grow at the 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. So, twice a year — on the anniversary and semiannual anniversary of its issue date — the Earnings Rate of your I Bond will change to reflect an adjustment for inflation. Remember, th fixed rate of return, the rate your bond earns over inflation, stays the same.