All sponsors must ensure that all non-EEA staff or potential recruits have current visas.
If an employee has applied for a new visa or an extension to their current one, and their current visa expires whilst their case is under consideration, it is the employers’ responsibility to check with the Home Office that they can continue to employ that person.
This can be done by logging on to https://www.gov.uk/view-right-to-work If the result is inconclusive it will lead you to a second link which is the employer checking service where further checks can be made: https://www.gov.uk/employee-immigration-employment-status
This enables UK employers to confirm whether a non-EEA national holding either a biometric residence permit or biometric residence card has a current right to work in the UK and whether they are subject to any restrictions.
From the end of January 2019, employers will be able to request either the online check or the existing document-based check; online checks will be a voluntary option whilst migrants and employers develop familiarity with the new service. The digital status checking services will provide a quick and secure verification of status.