You must check that every employee you employ has the right to work in the UK. The penalties for hiring illegal workers are considerable - up to two years in prison and up to £20,000 for each illegal worker, and an unlimited fine if you 'knowingly employed' the person.
An illegal worker is someone who is subject to immigration control, is aged over 16 and is not permited to do the work you want them to do. Illegal workers can include:
You can employ the following people without restriction:
However, you should still check the right to work in the UK of any potential employee claiming the right to work under one of these categories.
You can also find guidance on the documents you can check to prove someone's right to work in the UK on the GOV.UK website.