Though your card issuer generally cannot increase your interest rate on your existing balance (that is, on the amount you owed when the rate increase took effect), it can increase your interest rate for new transactions. The card issuer must give you advance notice. Once the new rate takes effect, it can be applied to any transactions that take place more than 14 days after the notice was sent.

If the card issuer raises your interest rate on new transactions, it generally must reconsider the rate increase at least once every six months to determine whether the reasons for the rate increase still apply or whether the rate you are being charged is the same as the rate that new cardholders like you are being charged.