Be wary of high interest rates on back-to-school store credit cards

Parents will spend an average of $688 on school supplies this year, which is up 60 percent compared to 10 years ago, according to the National Retail Federation.

The price might make people sign up for a store credit card to get a discount, but Consumer Reports money experts did their homework and said it might be wise to hold off.

Pencils and paper, backpacks and clothes, headphones and even laptops are just some of the items on many kids' back-to-school school supplies lists. Betsy Helmuth has a son in grade school and a daughter entering kindergarten, and even her list is long and pricey.

"Per kid, and I have two kids, I would say it's $130 to $200," Helmuth said.

So, those offers to save 20 percent by opening a store credit card can seem like a good deal.

"When you are at the register and you're going to spend a lot of money that you already feel a little bit uncomfortable about, and they tell you that there's a chance to get a deep discount, it's very tempting," Helmuth said.

For Helmuth, it's beyond tempting.

"I think I've applied to at least 10 of them," she said.

Signing on to those cards is probably not a good idea, according to Consumer Reports. The store card interest rates are often much higher: They average about 24 percent, which is well above the typical rate of about 15 percent.

Consumer Reports says that just applying for any new card can temporarily lower your credit score.

"Every time an inquiry is made on your credit card account it hurts it a little bit, and while it may not seem like that much, it could be the difference between a good credit score and a bad credit score," said Consumer Reports Money Editor Nikhil Hutheesing.

If you do open an account, don't shut it down immediately because that also has a negative impact on your credit score as well.

"The best thing to do is put the card away and don't use it," Hutheesing said.

Consumer Reports says store cards, which can be easier to get approved, could be a good way to get begin to build credit. For people who shop at the store often, the card can earn special discounts or points.

With the high interest rates, though, Consumer Reports it's especially important to pay your bill in full each month, so it doesn't undermine the reason you got the card in the first place.