Allow only new hires to have negative paid leave

Summary:

We are looking for a way to allow only new hires the ability to have a negative paid leave balance. We are a facility that is 24/7, but some areas are closed for holidays. If someone starts the week before/of a holiday, and are not able to work because their area is closed, we want to allow them to use paid leave they have yet to accumulate for convenience. Is this possible?

Content (required):

Version (include the version you are using, if applicable):

Code Snippet (add any code snippets that support your topic, if applicable):