Hidden fees abound in credit cards. They include fees for going over your credit limit, transferring your balance to another company and paying late. The only way you have of finding out about these fees is to call the issuer or read the microscopic print found on the original disclosure paperwork or monthly statements. You should also be aware that your card issuer can sell your account at any time to a company that will change every term you have including the interest rate. Be vigilant.