An illegal worker is an individual whose right to work has expired or alternatively, an individual who never had the right to work within the UK. This definition includes individuals who have entered the country illegally, or those who were granted leave to enter the UK, but have either overstayed past their visa expiry date or those who were granted leave subject to specific conditions which they are in breach of.
An individual does not need to have employee status in order to be regarded as an illegal worker. The offence of employing an illegal worker applies to any individual employed under a contract of employment, a contract of service or those undertaking an apprenticeship.