Through high fees and interest rates, Credit card companies are notorious for taking as much advantage of consumers as possible, within the limits of the law. So why not turn the tables?

In your dealings with credit card companies, there is a way that you can profit. It involves those convenience checks that credit cards send relentlessly as part of their balance transfer offers.

Instead of tearing up the convenience checks, be on the lookout for 0% APR offers. If you get one, here s the scheme: Write the check out to yourself and deposit it in a high-yield savings account. Then, before the promotional period expires, withdraw the amount needed to repay the balance. As for the interest accrued in the account? It s your gift.

Many people think balance-transfer checks can be made payable only to other credit card companies to pay off existing balances. Not so. In most cases, you can write such a check to pretty much anyone, including yourself, says Curtis Arnold, author of How You Can Profit From Credit Cards and founder of CardRatings.com, a Web site that compares credit-card offers. If you re careful, your credit cards just might be the cheapest sources of short-term borrowing around.

When Arnold and his wife got married, they used 0% APR convenience checks to pay for their wedding. "[It was a] cheap way to finance a wedding, which, as we discovered, can be a very costly undertaking," he says.

But while 0% APR convenience checks can be a means to lower interest payments or even make a quick buck, they can backfire on you if you're not aware of the pitfalls. Here's what you need to know about these offers and how to use them strategically.

Getting Into the Game

Credit-card companies are generous when it comes to balance-transfer offers. Most are at 0%, but they can be five percentage points or so higher. Whether you receive such solicitations depends on which card companies you use, as well as your credit history. But there is a way that you can increase the flow: When you get a new credit card, use it for the first couple of weeks, pay it off and let it sit idle for a while, leaving the credit-card company to worry that the card has been retired to the back of your wallet. Invariably, the checks will start to arrive.

The Fine Print

There's a good reason why credit-card companies clog their card members' mailboxes with 0% APR offers: if you read deep in the fine print, you'll see that those sweet deals can be a big moneymaker for the creditor.

The plumpest hens are those card members who already carry balances or continue charging in the future. That's because when you transfer a balance at a promotional rate, and your regular purchases carry a higher rate, your monthly payments will go toward the balance that carries the low, promotional rate.

In other words, if you transferred $10,000 to a card that carries a 13% APR for purchases and continued using the card, your monthly payments would apply to the $10,000 balance at 0% APR first, while your purchases would continue accruing interest. In effect, the true APR for your balance transfer would be higher than 0%. Bottom line: Whenever you're planning to transfer a balance, make sure the card that you're transferring to is paid off before the transfer is complete and then leave that card alone until it's time to pay the low-rate transfer off.

If you were to transfer $4,000 to a card that carries a 9.99% rate for new purchases and make the minimum monthly payments (usually these are 2% of the total credit card balance), you would accrue an estimated $3,550 in new charges (assuming you charge a mere $50 a month) while paying off the transferred balance. The true APR you'd pay in that scenario: 4.58%. That's still better than 9.99%, but it isn't the 0% APR deal you signed up for.

How Much Does That Balance Transfer Really Cost?

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