<prompt> Human: Hi all, Im not sure if this is too specificside-topic for this sub, please re-direct me if so. The last few months have been crazy busy in job and personal life for my wife especially, and she was about a week late with her credit card payments each month spending about 1,500 on them. I took a look at her statements recently to help us plan a shared budget for the new year -- and saw she was getting hit with roughly 10 in late fees and 20 in Interest Purchase Charge fees since October. She had a defeated call with Chase sales reps who waived one of 5 or 6 fees for her. I noticed her APY is 20.49, and started doing some math in my head, and thought this cant be right -- 20 over a YEAR cant then lead to 2 or 3 charges for being just a week overdue in payments. So today I went into a branch to find out what their math is: It turns out that Chase was charging her 112th of the 20.49 Annual Interest on each month that she made a late payment. So, effectively shes getting charged for being 30 days late every time shes 5 or 6 days late. And since this happened over a few months, she was getting charged roughly 90 days interest when she shouldve only been charged for 20 days interest. Obviously the first moral of the story is pay your credit card on time. But, given that my wifes bill has all sorts of daily balance method language, I think this is pretty nefarious dealings from them.  <response>: Thats typically how interest works. Read the credit card agreement - its probably in there in pretty plain terms.Credit cards are a really bad idea if you carry a balance. Really high interest. Usually compounded monthly sometimes daily tho. It makes it really hard to climb out. If she hasnt already - she should stop using the card and pay with cashdebit for things until she is no longer carrying a balance. 