It can be smart to do this, provided you don’t continue to add new charges to the card you paid off. If you open a balance transfer account to zero out an older credit card, you’re shifting debt from one location to another, not adding to your existing debt. When you pay on the balance transfer card, you reduce your debt. But if you add charges to the card you’ve paid off, you’re increasing your debt and that’s not the wisest personal finance move in this scenario.