<prompt> Human: So my coworker just had something happen that seems a bit shady to me. Im sure its legal but she is really upset right now and feels deceived. Several months back she financed a computer through Apple which goes through Barclaycard. The terms of the agreement are that if you pay the purchase off within a preset amount of time and no late payments that there is 0 interest. Well she has been paying on this for awhile now and this month made the mistake of making her payment 2 days late. Well she was under the impression that she would start accumulating interest now but instead they charged her the full back interest of over 500 this month which has put her over her limit. Does she have any recourse here or is this pretty much just a situation where she is SOL for not understanding the terms well enough? Assistant: Yes, unfortunately, it is completely legal. I read this a couple of months ago which explained how deferred interest works.Edit: If youve recently made a big purchase, chances are the retailer offered you a way to pay for it over time using a deferred-interest plan along the lines of no interest if paid in full in 12 months.What you may not realize: That offer is probably a credit card.Play by the rules, and you get a no-interest loan. However, if you go too late on a payment, misinterpret the payoff date or lose your ability to pay, you could end up with a hefty interest rate, plus retroactive interest added to the bill.Human: Wow, how crazy. With that in mind it seems like they arent really offering you anything. Pretty much every credit card Ive ever had has a year of 0 interest, difference being that no deferred interest would be added if a balance wasnt paid off by the time the year is up. She would have been better off just opening up some other credit card with a year of 0 interest and using that. How sneaky.  <response>: I know this sounds harsh, but thats not all that crazy. Many 0 lenders are this way. You are completely fine as long as you are within the TC. If you go over the promotional period or make a late payment, you get hit with all the deferred interest. Unfortunately, and this is the part that Im going to get downvoted for saying, your friend is 100 at fault for not understanding the terms and conditions as well as making a late payment. The lender made it very clear in the TC how this works. This is not predatory, and this is not uncommon at all. Dont sign up for things you dont 100 understand how they work. Lessons to be learned here. 