Calculating the Cash Advance Fee and the Dollar Amount of Interest. Sidney took a $200 advance by using checks linked to her credit card account. The bank charged a 2 percent cash advance fee on the amount borrowed and offers no grace period on cash advances. Sidney paid the balance in full when the bill arrived. What was the cash advance fee? What was the interest for one month at an 18 percent APR? What was the total amount she paid? What if she had made the purchase with her credit card and paid off the bill in full promptly?