Generally, an employer may not decrease an employer’s salary. However, this is subject to many different conditions. For example, the general principle is that an employer may not make unilateral changes to terms and conditions of employment (which include salary) unless the employee is first consulted on the proposed change, and agreement is obtained.
However, if an employee has been lawfully demoted for whatever reason, then obviously the salary applicable to the lower post will apply. There is no obligation on the employer to keep the employee on a salary applicable to a higher post than that occupied by the employee.
This sometimes happens where a sanction of demotion is applied in a disciplinary matter, as an alternative to dismissal. A demotion may also occur by mutual agreement in a case of incapacity – poor work performance – whereby it has been found that an employee is unable to properly perform in a certain post but is able to perform at a lower level. As an alternative to dismissal, the employee can accept the demotion, but the lower salary applicable to the lower post will apply.
The employee has no legal entitlement to demand that the salary applicable to the higher post or the previously occupied post be applied.