What is APR

The APR is a measure of the cost of credit, expressed as a yearly rate. It also must be disclosed before you become obligated on the account and on your account statements.

The card issuer also must disclose the "periodic rate" - the rate applied to your outstanding balance to figure the finance charge for each billing period.

Some credit card plans allow the issuer to change your APR when interest rates or other economic indicators - called indexes - change. Because the rate change is linked to the index's performance, these plans are called "variable rate" programs. Rate changes raise or lower the finance charge on your account. If you're considering a variable rate card, the issuer must also provide various information that discloses to you:

that the rate may change; and

how the rate is determined - which index is used and what additional amount, the "margin," is added to determine your new rate.

At the latest, you also must receive information, before you become obligated on the account, about any limitations on how much and how often your rate may change.