If your contract of employment is for a fixed-term (say, 12 months), or it is stated to last until a specified task has been completed, then the contract will automatically terminate at that point.
Most employment contracts, however, are not for a fixed-term. Instead, they simply continue until one of the parties, the employer or employee, gives notice to terminate. The contract should state the length of the notice period which either side must give before terminating. By law, there is a minimum requirement of not less than one week for each completed year of service (up to a maximum requirement of 12 weeks’ notice).
It is perhaps not well known that, in most cases, employees can simply walk away from an employment contract without giving the correct notice period. Although, this is technically a ‘breach of contract’ by the employee, there is usually no legal penalty which can be applied to an employee in this case. However, the same is not true for the employer who would have to pay compensation if they were to terminate without giving the correct notice period.
Even if the correct notice period is given by the employer, after two years have passed from the commencement of the employment, the employer is not permitted to terminate unless it does so for a ‘fair reason’ (see below). Otherwise, the employer may face a claim of ‘unfair dismissal’.