An employer may face a situation where a former employee makes a complaint.
There is no legal requirement for the employer to deal formally with the complaint. However, the employer may feel that it is appropriate to engage in dialogue with the individual in the hope of resolving a minor issue informally, without the need for the ex-employee to pursue tribunal or court proceedings.
There may be circumstances in which the employer should respond to a more serious complaint (for example, bullying). The former employee's complaint may highlight a serious problem in the workplace that the employer needs to address.