Where you have an under-performing staff member, action is required. It must be determined whether the employee is not able to perform the function, has misunderstood your requirements for the function, or just requires further training in meeting your expectations. Obviously this requires discussion, and - importantly, post discussion documentation. Identification of underperformance sometimes happens within the 90 Day trial, and sometimes does not.
No matter what the situation in terms of your employee's tenure with your business, if you have made the decision to place the employee in the role, you must also take responsibility for his or her training. In the instance where futher or corrective training is required, the process of what the expectation for the employee's performance must be clarified and documented. Training or corrective action to assist the employee in meeting the required standard must be agreed and made clear with correct documentation.
The importance of correct HR documentation is often misunderstood. If both the employer and the employee are to be working to the same agenda, there may be no misunderstanding - which does happen all too often. Written processes, signed and committed to by both parties gets a better overall outcome.