A balance transfer is the process of moving existing credit card debt from one or more cards to a new credit card, typically to take advantage of a lower or 0% introductory APR offer. Many balance transfer cards offer 0% interest for 12–21 months, giving borrowers a window to pay down debt without accruing additional interest. Balance transfers usually come with a fee of 3–5% of the transferred amount. The strategy works best when you have a clear repayment plan and can pay off the balance before the promotional period ends — at which point the regular APR kicks in.