Are credit cards for people with bad credit worth the high costs? According to one study, if your aim is to improve your credit score, yes, they are. The study was performed by the credit bureau TransUnion, which was commissioned by Citizens for Equal Access to Credit to conduct a study of 365,000 subprime cardholders over a two-year period.

Personal finance experts generally advise against closing credit cards, because reducing the total line of credit available to you may hurt your credit score. However, according to a new study by FICO, having a lower total revolving credit line may not necessarily affect your credit score. Credit scores will only suffer under some circumstances, for some types of cardholders.

In the current tight credit environment, keeping your credit score as high as possible is of critical importance. The rules for credit scores are changing. A credit score of 720 used to be considered Excellent, and would get you approved for loans and credit cards with the best terms. Nowadays, your credit score must upwards of 750 to be considered Excellent.

Credit scores typically range between 300 to 850, and a surprising number of things in your life depend on where your score falls in that range. Certainly, your credit score influences your ability to get a credit card or get approved for a new loan. However, your credit score also influences how much you’ll pay for car insurance, whether you’ll get approved for a cell phone, and it’s even considered when you apply for a job or for a rental.

If you have bad credit, one of the fastest ways to improve your credit score is to check your credit report for errors. Statistically speaking, 75% of credit reports contain errors, and some of these can easily pull down your credit score.