If your organisation permits employees to carry forward allowance to the following year, this can be configured within Settings of Timetastic.
For details on how to do this, see Setting your annual carry forward.
Amounts carried forward can also be edited after the year end run, on an individual employee basis.
To change this for an individual just head to USERS from the main navigation and select the relevant user.
Under the 'Allowance' tab, click into the 'Brought forward' box.
Edit as needed and click 'Update'.