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Recently, this has prompted a few to sweeten the deals being offered to new credit-card customers. These offers may look appealing at first glance, but it should be remembered that despite such appearances, paying credit-card interest remains a costly way to borrow money.

Something unusual happened to the average credit-card interest rates last month, as recorded by the Reserve Bank. They fell, for the first time in almost two years. Throughout the industry, the average rate for a low-rate card has also fallen by 0.25 percentage points from 13.2 to 12.95 per cent, after official interest rates were cut, the RBA said.

Finder.com.au reports that five credit cards have cut rates since the beginning of the year, suggesting that we shouldn't overstate the significance of this, and it may have been driven by a handful of lenders. Moreover, average rates on higher-end cards that offer rewards have not dropped.

Nonetheless, it's a change from what has been happening in the past couple of years. It also comes at a time when banks are trying to compete more on credit-card lending, with several offering interest-free periods when you transfer your balance.

Mozo.com.au says that last month Westpac and Suncorp extended the number of months they will give customers zero interest on balance transfers.

These offers might look tempting to some, but there are reasons to be sceptical. One is fees. Finder.com.au says many of these are changing, with 13 card providers raising their fees this year, while another nine are cutting them. That's a reminder to also look at the fees, alongside the other features being promoted.

More fundamentally, RBA governor Glenn Stevens also made some sensible points last month that put credit-card promotions in perspective. He pointed out that the main way in which banks compete is by offering a better deal to take your business elsewhere, rather than on low interest rates. So what? Well, he didn't say it, but the deals that try to encourage customers to transfer their balances are a calculated offer that's designed to look appealing, but is often still very expensive.

The 0 per cent interest rate often applies only to the balance, and a far higher rate is charged on new purchases. The banks offer the low rate only because they know that many people will not pay off their balance in time, and will therefore have to pay the much higher rate in the future.

Stevens was blunt on whether paying credit-card interest was a good idea, if you can avoid it. "I do not think we should be encouraging people to borrow on credit cards. It is an extremely expensive way of borrowing."

Too right. Banks are doing their best to make credit-card debt look tempting, but it's worth keeping warnings such as these in mind.