The rate you earn, either 1.5%, or 2%, is effective for a calendar month. However, credit card accounts cycle at various times throughout a month, so one statement can include activity across months. Say your earn rate was 2% in September and 1.5% in October, and your account cycles on the 23rd of each month. Your October statement would include transactions posted from Sept. 24 – 30 at 2%, and transactions posted from Oct. 1 – 23 at 1.5%. Also, the cash back rewards you earn for each purchase are based on the earn rate in effect when the transaction posts to the account, not the earn rate in effect when the transaction was authorized. That means it’s possible that a transaction authorized when the earn rate was 2% may post to the account when the earn rate is 1.5%.