This Practice Note considers how an employer should deal with the situation where it has identified that an employee does not have, or may not have, the right to work in the UK. It looks at employment status, the circumstances when a potential illegal worker may be identified and best practice on how to deal with the situation (including conducting an investigation and following a fair procedure). The Practice Note also discusses various scenarios which may arise in practice, including where an employee may not have the right to work due to matters which were in control of the employer, and circumstances where a person may have a right to reside and work in the UK that is not immediately apparent on the face of their documents (eg which stems from an entitlement to British citizenship). It also considers the various employment law issues that may be relevant, including unfair dismissal, discrimination and breach of contract.