7 On Your Side: The 7 times you should never pay with credit cards

NEW YORK (WABC) -- Using a credit card has its advantages, but not always. And there are many occasions where you definitely don't want to pull out the plastic.

It's attractive to get now and pay later, especially when you earn points toward free stuff while you're at it. But with extra fees and higher interest, you have to think before you swipe.

If you're swipe happy, studies show using credit cards just for rewards points causes people to spend more money.

"Keep in mind the economics of the credit card the merchant pays the credit card company," said Scott Gamm, Economics Reporter for TheStreet.com. "They're making money every time you swipe that card."

Gamm warns that charging your way to reap rewards will put you in debt.

"Just because you're getting rewards doesn't mean it's in your best interest," he said.

Speaking of interest, don't charge payments due on either student loans or tuition.

"The point here is, why trade low interest debt for high interest debt?" he said.

Most credit cards charge between 15 to 20 percent interest, while working out a plan with the bursar's office may be 0 percent. And remember, student loans may often have deferment lifelines in case you can't pay right away.

"Not all student loans are created equal," Gamm said. "Keep in mind some require you to pay immediately some not until you graduate."

Scott says also avoid charging large medical or hospital bills on high-interest cards.

"When you have medical bills, contact the hospital first and say here's why I cant pay now," he said. "Is there anyway to restructure the debt? What kind of payment plan can you put me on?"

Doctor's offices are also willing to settle debt for little or no interest. But if you get on a payment plan, don't charge the payments.

"All of a sudden, you've turned a 0 percent interest into 20 percent," he said. "And that doesn't make any sense."

What else doesn't make sense to charge those dollars to Uncle Sam. Don't charge your taxes.

"They might be charging a 2 percent fee on top of that," Gamm said. "And we all know how much IRS bills are for taxes that could add up significantly."

The same goes for high fees attached to charging your mortgages via a third party lender. The same warning goes for charging a new or used car, in full. If you find a dealer willing to let you do it, fees can add thousands onto that automobile and max out your credit quick.

The big takeway is that there are things you pay for with credit, not debit or cash.

Some credit cards offer warranties on big ticket items like appliances. Also, if you're shopping online, you have plenty of credit card protections when it comes to potential fraud. You're much more likely to get your money back in a dispute if you used credit.