As an admin, you can set what happens to your employees' unused leave balance once the leave period ends. 

Go to Leave > Leave Settings > Leave Types > select the relevant leave type under My Company Leave Types (usually, this applies to annual leave) and click on the Edit button to edit it. 

This will bring up a pop-up to edit the leave type's settings.

Scroll to the Unused leaves section and choose the Carry forward option. You can set a time period within which the carry forward leave must be used, and the carry forward leave balance limit can be set either in days or a percentage

First, you will need to deactivate the Leave Period so that employees will not be able to apply for leave anymore.

Go to Leave Settings > Leave Periods > click the 3 dots menu on the relevant leave period > click on Deactivate.

Then, add a new Leave Period for the upcoming Leave Period that you wish to carry forward the leave balance to. 

Go to Leave > Leave Settings > Leave Periods > click the Add new Leave Period button.

Select the start date and end date of the Leave Period, as well as the Leave Types that should be available within the Leave Period. Click the Save button to finish setting up the Leave Period.

Once the new Leave Period has been set up, click on the 3 dots menu on the relevant leave period > click on the carry forward option