If a member of staff resigns but does not work out their notice period, where does the company stand with regards to retaining the equivalent amount of money had the employee worked their notice from monies owed to them?

I’ve been told to hold back holiday pay owed to someone who left without giving notice, and even though we should pay it to them, I have been told to wait and see if they ask for it. I’d appreciate anyone’s thoughts and views on this.
Kelly Bennett