Minimum payment due, reads the box on your credit-card statement. What an enticing idea: Pay a small amount and you’re off the hook for the whole bill—for a while, anyway. Alas, as the more than 45% of Americans who carry a balance every month know, that rotating charge usually comes back to bite you. For example, a cardholder who owes $15,956—the average amount of debt per household, according to Ben Woolsey, the director of marketing and consumer research for CreditCards.com, a credit-card comparison site, will end up shelling out an additional $11,000 in total interest if she pays only the minimum each month.

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