...
On 23 September, there's only 12 minutes worth of working hours left. On 24 September, which is another new working day, we will get a full 8 hours from it. We have 8 hours and 12 minutes now and need another 1 hour 48 minutes. Effectively, the due date would be on 25 September, 9:48am.
Related Documentation
...
Deadlines act as a timer which triggers an exception transition to another activity when a specified duration has elapsed.