Q. Is it a good idea to get credit cards with no interest and just close them and open new ones when the no-interest period ends? I heard that even if I close a card, it will always show a credit line open. Is this true, or is it OK to keep rotating cards as I've been doing?

A. Transferring debt from a high-interest credit card to a no-interest credit card can be a smart thing to do. Find out more by reading our advice on the best cards for balance transfers.

But what you heard about the credit limit remaining open after the card is cancelled is incorrect. If the cancellation is done properly, your credit line for that account should be zero.

However, repeatedly rotating credit cards could hurt your credit score in several other ways.

About 30% of your FICO score -- the most widely used credit score, calculated using a formula created by Fair Isaac Corp. -- depends on how much of your available credit you've used. When you close an account, you reduce your total available credit. If you're carrying a balance on other credit cards, you've just increased the percentage of available credit you've used.

For example, if you've got several cards with a total credit line of $30,000 and a balance of $10,000, you've used 33% of your available credit. Now, if you close one of the accounts with a $10,000 credit limit, you're suddenly using 50% of your available credit. FICO begins to penalize you anytime you borrow more than half of your available credit.

About 10% of your score depends on how recently you took out a new loan or opened a new credit card account. But even credit report inquiries by someone checking your credit history when you are trying to obtain credit will lower your score by about 10 points.

Finally, repeatedly opening and closing credit card accounts raises the risk of errors cropping up on the reports used to calculate your score. If one of the agencies incorrectly labels one of your old accounts as "closed by creditor," that counts as a bad debt.

Here's how to get free copies of your credit reports to see where you stand.