The bond rates are set per 6 month window - but you get it relative to the purchase date. So if you buy before the last possible day before the rate change date you would get 7.12% (annualized) for 6 months then 9.6% (annualized) for 6 months. If you buy after the rate change, you would get 9.6% (annualized) followed by some yet to be determined yield for 6 months.