How does a 0% intro APR credit card work?

Question

ClearValue Editorial Team · Accepted Answer

You get a promotional window — typically 12 to 21 months — during which new purchases (and often balance transfers) accrue no interest. When the window ends, the ongoing variable APR applies to whatever balance remains. It's a tool if you have a payoff plan and a trap if you don't. A 0% intro APR is an interest-free runway, not free money. On purchases, it lets you spread a large expense over the promo window with no finance charge — as long as you clear the balance before it ends. On balance transfers, you move a high-APR balance onto the card and pay it down interest-free, but a transfer fee (usually 3-5%) applies, so math it against your interest savings first. Two things to watch: (1) the ongoing APR that kicks in after the promo can be high — always check the full range, not just the floor; (2) missing a payment can void the promo APR entirely on some cards. Set the payoff so the balance hits zero a month before the intro period ends, and treat the promo as a deadline, not a suggestion.