If you cancel a course after the drop/add deadline do you get charged extra for cancelling courses?


Also, if you don't pay that outstanding amount (if you do have money you owe) do you get interest charged on it? Or late fees?

You won't get charged extra you will only have to pay for the proportion of your time you were in the class and get refunded the rest. If you get OSAP that might become a problem with a loan overcharge and you have to pay it back but you don't have to pay them back for your first overcharge.