We charge 1.75%/month compounded monthly(23.15)annum on unpaid accounts after 30 days.  At the end of the month we make up an invoice to the customer as per interest showing on their statement. Now it looks like on the statement each month they are compounding monthly but at the yearly rate - why?? And after reviewing this I see that our staff have been charging this to the customer which is way out of balance - what is causing this.