For the purposes of this legislation redundancy means 'dismissal for a reason not related to the individual concerned' echoing article 1 of Directive 98/58/EC concerning collective redundancies. Redundancy is defined in UK law under the Employment Rights Act 1996 - Part XI, chapter II, section 139. 

Collective redundancies differ from individual redundancy situations within UK law in respect of procedures which must be followed. The duty to consult is set out in Trade Union and Labour Relations (Consolidation) Act 1992 Part IV, chapter II, section 188. A distinction is made between establishing entitlement to redundancy payments (which is irrespective of the numbers to be made redundant) and the right to be consulted. A collective redundancy situation arises when an employer, regardless of size, plans to dismiss as redundant 20 or more employees at one establishment within a period of 90 days or less. This definition is important because it provides a broader requirement for consultation. For example, in addition to employees who may be dismissed by reason of redundancy, this legislation also applies where an employer decides to offer alternative employment or change an employee's terms and conditions (such as changes to wages, hours of work or duties) by giving lawful termination of their contracts and reengaging them on different terms and conditions.

The employer has a duty to consult with the appropriate representatives of the employees (trade unions or other elected employee representatives, or information and consultation bodies in companies with more than 50 employees) who may be affected by the planned dismissals or may be affected by measures taken in connection with those dismissals. Procedures for consulting with employees on fixed-term contracts do not apply unless the employer is proposing to dismiss the employees as redundant and the dismissal will take effect before expiry of the fixed-term contract. 

Non-employees, police, members of the armed forces, parliamentary staff plus a few other categories of workers are excluded from the legislation.