How do 0% APR balance transfer cards work?

A balance transfer card lets you move existing credit card debt onto a new card that charges 0% interest for a promotional period, typically 15 to 21 months. During that window, every dollar you pay goes toward reducing your balance instead of paying interest. It's one of the most effective debt tools available if you can qualify.

The mechanics are simple. You apply for the card, get approved, then request a transfer of your existing balances (either during the application or shortly after). The new card pays off your old cards directly. Now you owe the same amount, but at 0% instead of 22% to 28%.

The costs: Most balance transfer cards charge a transfer fee of 3% to 5% of the amount transferred. On a $10,000 transfer, that's $300 to $500 added to your balance. Even with that fee, you're saving far more than you'd pay in interest on the original cards. A $10,000 balance at 24% generates $2,400 in interest per year. Paying $400 to avoid that is a clear win.

The trap: After the promotional period ends, the interest rate jumps to the card's regular APR, typically 20% to 28%. Any remaining balance starts accruing interest at that rate. If you haven't paid off the transferred balance within the promotional window, you're back where you started (or worse, because now you might have even more cards open).

The math you need to do: Divide your total transfer amount by the number of promotional months. On $10,000 with an 18-month 0% period, you need to pay about $556 per month to clear it before the rate jumps. If that payment fits your budget, the strategy works beautifully. If it doesn't, you'll still save significant interest during the promo period, just be prepared for what comes after.

Who qualifies: You typically need a credit score of 700+ for the best balance transfer offers. Some cards accept scores in the 670 to 699 range but with shorter promo periods or higher transfer fees. If your score is below 670, balance transfer cards are unlikely to be an option.

One critical rule: do not use the balance transfer card for new purchases. Many cards apply payments to the 0% transfer balance first, meaning new purchases accrue interest at the regular rate until the transfer is fully paid off. Sock the card in a drawer and only use it for the balance payoff.