Overtime can be voluntary (it may be offered or requested by an employer during very busy periods) or compulsory (it can be guaranteed or non-guaranteed). It will depend on the terms and conditions of the contract whether overtime is:
- compulsory and guaranteed
- compulsory but non-guaranteed
An employer who wants to rely on either guaranteed or non-guaranteed overtime should clearly set out in the terms and conditions of employment that the overtime is compulsory.
If a worker refuses to work overtime that they are obliged to work according to the terms and conditions of their employment (ie their employment contract states they must work overtime), the employer may view this as a breach of the contract and a disciplinary matter.
Unless overtime is guaranteed, employers can stop employees from working overtime. However, employers cannot discriminate against anyone, for example, by stopping some employees from working overtime while letting others do so.
Voluntary overtime is where an employer has no obligation to offer overtime and there is no obligation on the worker to do the overtime. It’s up to the worker to decide whether they want to participate in the extra work or not. However, workers should not be treated less favourably or unfairly for rejecting voluntary overtime.
Voluntary overtime may be used where several employees are absent from work which leaves the employer under-staffed. The employer may then offer overtime to continue to meet customer demands. The workers are able to choose whether or not to work the extra hours as there is nothing in their contract to say they must do so.
Guaranteed overtime is where an employer is contractually obliged to offer the extra work and the employee is obliged to accept it. For example, if an employer knows they have work due at a particular deadline each month, the employee’s contract will include an express clause outlining that they are obliged to work extra time each month around the particular deadline.
Non-guaranteed overtime is where an employer may or may not offer overtime to an employee, but when it is offered the employee must accept it. For example, an employer knows that their business is likely to be busier at certain times of the year but they do not know exactly how much overtime will be needed to complete the work. The employee’s contract will include that, if needed, they will have to work the extra hours. For example, that 'reasonable overtime may from time to time be required, in accordance with the needs of the business'.