If someone is underperforming at what stage do you start formal disciplinary procedures?

There is no precise time period, statutory or otherwise, for determining when an underperforming employee should be subjected to a formal disciplinary procedure on the grounds of poor performance. A number of factors should be taken into account by an employer when determining the reasonableness of any actions to be taken in respect of an underperforming employee including, but not limited to, the employee's length of service, the complexity/difficulty of the particular role and work at issue, the requirement for additional training and the personal circumstances of the employee, e.g. personal issues such as a bereavement, disability etc.

Underperformance should be managed progressively and