You must check that a job applicant is allowed to work for you in the UK before you employ them.
You can:
You can also check an applicant’s right to work by using an identity service provider that offers Identity Document Validation Technology (IDVT). You can find out more about IDVT in the https://www.gov.uk/government/publications/right-to-work-checks-employers-guide
You do not need to do checks for existing employees from the EU, EEA or Switzerland if they came to the UK before 1 July 2021.
Irish citizens can use their Irish passport and passport card to prove their right to work.
You will need a sponsor licence to employ EEA and Swiss citizens coming to the UK to work from 1 January 2021 https://www.gov.uk/uk-visa-sponsorship-employers