Q. A store cashier offered me 10 percent off if I bought my new TV using a store credit card I could open on the spot, but I passed. Did I miss a deal?

A. That depends on whether you pay off your credit card bill in full every month. If you don't, you should avoid store cards because you'll pay interest rates that are higher on average than those of ordinary credit cards, and may wipe out any discount offered for taking out the card.

A 2016 survey by CreditCards.com found that store cards charge an average annual percentage rate of 23.84 percent—well above the national average of 15.77 percent for credit cards.

But if you’re sure that you'll be able to make your payments in full, it can be worth getting a store credit card, especially if it puts a few hundred dollars in your pocket, says Michael Saccucci, Ph.D., CR’s director of statistics. There's an additional benefit: If you need to build a credit history or improve your credit score, it can be easier to be approved for a store card than for a regular credit card. 

If you run into problems paying the balance later, Saccucci suggests shifting the debt to a fee-free balance transfer card with a 0 percent rate. Then hide your store card somewhere safe so that you won't be tempted to use it anymore. There's usually no cost to keeping a store card once the balance is paid, but canceling it can indeed ding your credit score. That's because your FICO score gets a boost the greater your total unused credit line is compared with your credit card debt.

For more information, check our store credit card buying guide.

Editor's Note: This article also appeared in the August 2017 issue of Consumer Reports magazine.