Q. I've been trying to help my boyfriend with his credit cards. When he sends in a payment, I noticed that it's applied to the lowest interest rate balances and the higher interest rate balances keep going up. A couple of years ago, the cash advance balance was $1,900. Now it's $3,500. How can his balance keep going up?

A. For years, credit cards have routinely applied payments in excess of the monthly interest charge to those balances charged the lowest interest rate.

That's usually the rate they impose on purchases. Obtaining cash with your credit card is usually the most expensive transaction you can make with a credit card.

Those loans carry a higher interest rate -- 20% or more at most cards -- and consumers who carry a balance on their purchases never have a chance to pay down, much less pay off, the cash advances they've taken out.

Although credit cards require you to pay the interest on your purchase balance each month, the interest imposed on high-cost cash advances can be added to that balance.

As a result, you can be current on your bill but plunging further into debt, as you've unfortunately seen with your boyfriend's account. And yes, you wind up paying interest on the interest.

The good news is that the Credit Card Accountability, Responsibility and Disclosure Act that Congress passed this spring will put an end to this billing practice. When it takes full effect next year, credit cards must apply all payments in excess of the monthly interest charges to the debt being charged the highest (not the lowest) interest rate.

But you can't wait for that to help you out. You need to do something right now.

The best solution would be to transfer your boyfriend's balance to a credit card that offers special deals for consumers who want to transfer balances from another card.

Check your mailbox for such offers, or go to Interest.com's database of credit card rates and terms, and look for the best deals on balance transfers.

The introductory rates can be as low as 0% for the first six months, or 3.99% for the first 12 months. Sooner or later, the regular rates will kick in, but 10.99%, 15.25% or 17.99% (depending on his credit score) would still be a lot less than what he's paying now.

The sooner he acts, the more he will save.