FIA card service charges retroactive interest. For example, if I spend {$100.00} in XX/XX/XXXX, and payment for that is due on XXXX XXXX. If I pay on XXXX XXXX, I 'm charged for 13 days of interest, rather than one day of interest. Paying three days late therefore comes to an annualized rate of ~140 %. It 's disgustingly predatory. 
