If you don’t pay off your balance transfer within the 0% intro period, you might end up paying even more in interest than you initially would have had you just stuck to the old card. Balance transfer cards are really useful and can completely recuperate your financial health, but only if you use them the way they’re intended. If you see them as an excuse to spend more and take a longer time to pay off your debt, you’re likely to end up in an even bigger debt.