If you consistently pay only the minimum amount due on your credit card accounts, your balance is close to your credit limit, and your credit score is nothing to rave about, you’re wasting an awful lot of money on finance charges.

How much? Look on your statement to find the amount you paid in finance charges last year, or call the card issuer to find out.

But don’t envy those who can easily pay their credit card bills on time and in full each month, and have great credit. A new study by Fair Isaac Co., creator of the FICO score, shows that 11% of U.S. cardholders—22 million people—had their credit lines reduced or their accounts closed between May and October of 2008.

How come? Because they weren’t generating enough profit for the credit issuers!

They were paying little or nothing in finance charges and no penalty fees, and therefore were not the kind of customers that credit card issuers prefer.

So no matter how poorly or splendidly you manage credit, you’re at the mercy of the few who control the credit industry. Not only do they make the rules, they’re free to change them at any time—in their favor, of course!

Here’s an actual quote from a major bank’s credit card application: “The terms of your account, including the APRs, are subject to change. This means that the APRs for this offer are not guaranteed; APRs may change to higher APRs, fixed APRs may change to variable APRs, or variable APRs may change to fixed APRs. We reserve the right to change the terms (including the APRs) at any time for any reason, in addition to APR increases that may occur for failure to comply with the terms of your account.”

Also: “If an account is opened, you will receive a Cardmember Agreement with your card(s). By using the account or any card, you agree to the terms of the Cardmember Agreement....You authorize us to allocate your payments and credits in a way that is most favorable to us. For example, to apply your payments and credits to balances with lower APRs (such as promotional APRs) before balances with higher APRs.”

So you end up paying more. And unless you’re willing and able to pay cash for everything, there’s nothing you can do about it.