Deferred Interest Promo Cost Calculator

About this calculator

Deferred-interest promotions — common on store credit cards for furniture, electronics and medical financing — advertise “no interest if paid in full” within a set promo period, but the fine print matters: interest actually accrues from the original purchase date at the card’s regular APR, it’s just waived if you clear the balance before the deadline. If even a small balance remains when the promo ends, the issuer charges retroactive interest on the entire original amount for the whole promo period, not just on the leftover balance.

This is very different from a standard 0% APR offer, where interest simply starts accruing going forward after the promo ends. Consumer advocates and credit counselors warn about deferred-interest cards for exactly this reason. This calculator takes your balance, the promo APR, and the promo length in months to estimate the retroactive interest charge you’d be hit with if the balance isn’t paid off in time, so you can see what’s at stake before you rely on a “no interest” offer.