All students are required to abide by the published Academic Calendar which shows when students can add and drop classes, avoid W's and get refunds for full semester length classes. (For short/late/summer starting classes, please refer to the date links listed under the "Date Begin/End" column located in the online schedule of classes)
If you add or drop a class after the published refund deadline (which is 10% of the term), you will be responsible for the enrollment fees associated with that course. Even if you have postponed your fees and have not technically paid for the class yet, the fees will remain on your account because you failed to drop the course before the published refund deadline.