At checkout, it can sound tempting to sign up for a store-branded credit card and score an instant discount, but consumer experts warn it could cost you big in the long run.

During the holiday shopping season, many retailers push promotions to sign up for their credit cards — often dangling deals like 10%, 15%, or even 20% off your purchase.

But surveys show plenty of shoppers wind up regretting it. Bankrate's Ted Rossman says that's because those perks often come with a steep price.

"Retail cards charge higher interest rates generally, because they're easier to get," Rossman said. "For a lot of people, this is their first credit card."

The promised discounts sound great, but if you don't pay the balance in full every month, it will cost you.

Currently, retail credit cards carry interest rates averaging more than 30%, according to a new Bankrate survey. That's much higher than the already steep 20% average interest rate on standard credit cards.

Home improvement stores and jewelry stores tend to carry some of the highest rates because you're usually using them to purchase big-ticket items, Rossman said.

Store credit cards are also known as closed-loop cards, meaning they can only be used at the specific retailer.

To make a store card work for you:

• Don't carry a balance
• Watch your spending limit
• Beware of deferred interest

Store credit cards typically carry much lower spending limits than standard cards. Spending just a few hundred dollars could easily use up 50-60% of your available credit. That can negatively impact your credit score by increasing your utilization ratio.

Cards with deferred interest often come with 0% promotional APR offers. But if you don't pay off the entire balance within the promotion window, you could owe retroactive interest on the entire purchase.

"I do hear those horror stories, you know, you had a $5,000 balance and you paid down all but $10 and, oh, wait, they go back and they charge you the average daily balance multiplied by the daily interest rate," Rossman said. "That's a really nasty gotcha."

A better option is a standard credit card with a 0% introductory APR offer.

Still, Rossman says store cards can pay off for loyal shoppers.

"You always shop at Amazon or Target or Best Buy, and you're going to enjoy getting 5% back on their card every time you use it," he said. "Again, you have to pay in full for it to be worth it."

You can also consider co-branded cards, like the Amazon Prime Visa. You get the perks of the brand, Rossman said, and you have the flexibility to use the card anywhere instead of being limited to the specific retailer.

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