The library system uses potential and active fines, which are processed at different times, to calculate the total fine.
Potential fines
These fines accumulate while a book is still overdue, but they do not become active until the item is actually returned.
The system cannot predict when you will bring a book back, so it can only calculate the total fine once the item is returned. You can check potential fines in your My Library account under your list of loans.
Active fines
These are fines that have already been accrued (see more info on when fines are applied).
Once you return the item, any potential fine that had been accumulating becomes an active fine.
For book renewals, please remember that up to 21 daysafter a book becomes overdue, you can still renew it, but fines will be charged retroactively from the original due date. To avoid fines, renew your books on time or within the 5‑day grace period after the due date.