Balance transfer cards explained

A balance transfer card offers a promotional 0% APR (typically 12–21 months) on balances you move over from other credit cards. If used correctly, it can save hundreds or thousands in interest while you pay down principal aggressively. If used carelessly, it's a slow-motion disaster.

The math

Most transfer cards charge a fee of 3–5% on the transferred balance upfront. If you're moving $10,000 from a 24% APR card to a 0% card for 18 months, the fee is $300–500. Interest avoided: roughly $2,000+ at 24%. Net savings: massive. But only if you actually pay off the balance during the promo period.

The trap

At the end of the promo, any remaining balance starts accruing interest at the regular APR — often 22–29%. Worse, most cards have 'deferred interest' provisions where, if you don't pay in full, they charge you interest going back to day 1. That makes the card more expensive than the one you transferred from. Read the terms carefully.

Don't add new debt to the transfer card

A common mistake: transferring the balance, then using the new card for purchases, then paying it down only to discover 'new purchases' often have a different (high) rate. Treat the transfer card as a payoff vehicle only. New purchases go on a different card.