The maximum credit card interest rate that a national bank may charge is generally determined by the law of the state where the national bank has its designated headquarters.
Under certain circumstances, a national bank may charge rates permitted by the law of a state where it has branches, even though its designated headquarters is located in another state. In both situations the rates can be charged no matter where the borrower resides.
You should review your account agreement, which is the contract governing your account, or any subsequent notifications regarding your account. These documents should provide information on which state's law will apply.