I am questioning the way Citi calculate the revolving balance. I did not make a full payment in XX/XX/XXXX XXXX actually I made a payment a little less than the statement balance way before the due, but forgot to pay the rest part because there is no reminder from citi telling me i had a remaining balance ). So they charged an interest on me. Then in XX/XX/XXXX after the new statement came out I made full payment but Citi still charged interest on my account which i totally do n't understand. I called them. The customer service said once you have revolving balance, interest will be charged until the 2nd billing cycle even if I paid off the balance, which sounds quite ridiculous. I asked for waiving the interest charge which my other credit card company like XXXX and XXXX allows, but got refused by Citi. I do n't know how the balance was calculated and I was never told before this call. Just want users to be careful when using Citi 's card. Their rules are not clear to you until you got hurt. 
