The interest rates on credit card are based on the risk levels. Credit card companies will use the credit score to gauge the risk and set the interest rates. If you have a low credit score, you are considered to be a greater risk, due to credit mistakes from your past. With this in mind, your low credit score will cause you to pay higher interest rates, as compensation for any risk of defaulting or making late payments. On the other hand, any consumer that has a high credit score will have a lower risk level, and due to their great credit history, they will get lower interest rates when they borrow money.