I visited the bank this week. My current rate expires soon. I didn't want to change the term, I knew the rate I wanted and I also requested a figure for borrowing some more (at the same rate). This is the reply I got when I emailed him after the appointment when requesting to know how much interest I would be paying: "Regarding your question about how much interest you will pay back over the duration of the mortgage term, this is actually a very difficult question to answer due to a term called compounded interest. Essentially, your mortgage generates interest on a daily basis which in turn changes depending upon your mortgage balance as well as the amount of days in the month i.e. the mortgage will generate more interest in January than it would in February. Because of this, I cannot give you a definitive answer to your question because your mortgage balance, and subsequent interest this generates, will change slightly from month to month and never remains stable." What do you make of that reply? I'd have thought it would be relatively easy to work this out given no variables. I haven't bothered trying myself but I did cover compound interest in school though I'm a bit rusty on it.