We have a clause in the contract of employment which is also listed on the letter of engagement which sets out the company's right to withhold salary equal to any shortfall in the minimum notice period given by the exiting employee. We have never had this tested but have previously taken advice. We are not looking to use this as a punitive measure but rather to offset some of the costs in replacing the exiting employee and for covering their notice period. Post interview and offer, the employee was on one month's notice at their previous employer. In the interim, the employee was looking for more hours so we decided to let them attend another branch on Saturdays. This went well. However, after one day working full time in the main office, they said "see you tomorrow" and never came back. They did not respond to phone calls, emails or text messages save one "personal reasons - won't be coming back" response. Cut and dry we thought. No notice given, only 4 days worked, minimum notice required is one week so technically, they owe us one day's pay, which of course we would not chase. However, they are now emailing demanding payment. We have not responded as the pay date is 31/12/16. The sums involved are not huge, around £300 or so but after costs to find the candidate, waiting for them to complete notice and now having to pay others to cover the hours they were supposed to do, I find myself drawn to the view that no, we will not bend over and let this slide. Principle, not financial. However, I see the potential downfall. Though we issued the letter of engagement we did not get a signature confirming receipt. We have remedied this going forward. The contract of employment was being completed and had not been issued, hence the retention clause outlined in the letter of engagement. I believe we have a defensible position should any any action be taken against us and whilst I am not unduly worried about any time taken to defend any action, I do concern myself with the fact that if costs were £10k then the risk / reward would mean that we would need to simply pay. Though potentially not material to this case, I actually think we have been led on here. I am not certain the ex employee actually left their prior employment and that they may have simply been using us to get weekend work. The tone of the emails received last week has been heavy on the "I have copies of the timesheets" etc. Thoughts ?