Yep. This is true whether or not you normally carry a balance. If you normally carry a balance, then the extra interest for paying a day late isn't a big deal: it's one day of interest. But if you normally pay in full, then it's effectively a month of interest for that day-late payment. Almost all "revolving credit" accounts work this way. In the 1990's, Amex had a product that didn't do this: Amex True Grace card. You got the interest-free grace period on new charges whether or not there was an unpaid previous balance. I never had one, but I suspect that even with that card you would find yourself with a loss of grace if you paid late.